utils/check-package: check all shell scripts

Currently only SysV init scripts are checked using shellcheck and a few
other rules (e.g. variable naming, file naming).

Extend the check using shellcheck to all shell scripts in the tree.
This is actually limited to the list of directories that check-package
knows that can check, but that list can be expanded later.

In order to apply the check to all shell scripts, use python3-magic to
determine the file type. Unfortunately, there are two different python
modules called "magic". Support both by detecting which one is installed
and defining get_filetype accordingly.

Keep testing first for name pattern, and only in the case there is no
match, check the file type. This ensures, for instance, that SysV
init scripts follow specific rules.

Apply these checks for shell scripts:
 - shellcheck;
 - trailing space;
 - consecutive empty lines;
 - empty last line on file;
 - newline at end of file.

Update the list of ignored warnings.

Do not add unit tests since no function was added, they were just
reused.
But expand the runtime test for check-package using as fixture a file
that generates a shellcheck warning.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
[Arnout: support both variants of the "magic" module]
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

.checkpackageignore

@@ -16,11 +16,13 @@ package/busybox/S02sysctl Variables
 package/busybox/S10mdev ConsecutiveEmptyLines Indent Shellcheck
 package/busybox/S15watchdog Indent Variables
 package/busybox/S50telnet Indent Shellcheck Variables
+package/busybox/udhcpc.script Shellcheck
 package/c-icap/S96cicap Indent Shellcheck Variables
 package/cfm/S65cfm Indent Variables
 package/cgroupfs-mount/S30cgroupfs Indent Shellcheck Variables
 package/chrony/S49chrony Indent Shellcheck Variables
 package/connman/S45connman Variables
+package/coremark-pro/coremark-pro.sh.in Shellcheck
 package/curlftpfs/0001-fix-CURLOPT_INFILESIZE.patch Sob
 package/curlftpfs/0002-free_ftpfs_file-memleak-fix.patch Sob
 package/curlftpfs/0003-nocache-memleak-fix.patch Sob
@@ -30,6 +32,7 @@ package/dbus/S30dbus Indent Shellcheck TrailingSpace Variables
 package/dcron/S90dcron Variables
 package/dhcp/S80dhcp-relay Shellcheck Variables
 package/dhcp/S80dhcp-server Shellcheck Variables
+package/dhcp/dhclient-script Shellcheck TrailingSpace
 package/dhcpcd/S41dhcpcd Indent Variables
 package/dhrystone/0001-cmdline-nruns.patch Sob
 package/dhrystone/0002-HZ.patch Sob
@@ -41,12 +44,15 @@ package/dmraid/S20dmraid Variables
 package/dnsmasq/S80dnsmasq Shellcheck Variables
 package/docker-engine/S60dockerd Indent Shellcheck Variables
 package/domoticz/S99domoticz Shellcheck
+package/dracut/merged-usr-module-setup.sh Shellcheck
 package/dropbear/S50dropbear Indent Shellcheck Variables
 package/earlyoom/S02earlyoom Indent Shellcheck
 package/ejabberd/S50ejabberd Indent Shellcheck Variables
+package/ejabberd/check-erlang-lib Shellcheck
 package/eudev/S10udev ConsecutiveEmptyLines Indent Shellcheck Variables
 package/exim/S86exim Indent Variables
 package/fail2ban/S60fail2ban Shellcheck Variables
+package/fakedate/fakedate Shellcheck
 package/fbv/0001-cross.patch Sob
 package/fbv/0002-fix-24bpp-support-on-big-endian.patch Sob
 package/fbv/0005-include.patch Sob
@@ -56,6 +62,7 @@ package/gamin/0002-no-const-return.patch Sob
 package/gcc/arc-2020.09-release/0002-libsanitizer-Remove-cyclades-from-libsanitizer.patch Sob
 package/genromfs/0001-build-system.patch Sob
 package/gerbera/S99gerbera Indent
+package/google-breakpad/gen-syms.sh Shellcheck
 package/gpsd/S50gpsd Indent Shellcheck Variables
 package/haveged/S21haveged Shellcheck Variables
 package/htpdate/S43htpdate Shellcheck
@@ -63,8 +70,12 @@ package/i2pd/S99i2pd Indent Shellcheck Variables
 package/ifplugd/0001-cross.patch Sob
 package/ifplugd/0002-fix-headers.patch Sob
 package/ifupdown-scripts/S40network EmptyLastLine Indent Shellcheck Variables
+package/ifupdown-scripts/network/if-pre-up.d/wait_iface EmptyLastLine Shellcheck
+package/ifupdown-scripts/nfs_check Shellcheck
 package/igd2-for-linux/S99upnpd Indent Shellcheck Variables
 package/inadyn/S70inadyn Indent NotExecutable
+package/initscripts/init.d/rcK ConsecutiveEmptyLines EmptyLastLine Shellcheck
+package/initscripts/init.d/rcS ConsecutiveEmptyLines EmptyLastLine Shellcheck
 package/input-event-daemon/S99input-event-daemon ConsecutiveEmptyLines Indent Variables
 package/iptables/S35iptables Shellcheck
 package/irda-utils/0001-daemon.patch Sob
@@ -94,6 +105,7 @@ package/lldpd/S60lldpd Indent Shellcheck Variables
 package/lockfile-progs/0001-sus3v-legacy.patch Sob
 package/madplay/0001-switch-to-new-alsa-api.patch Sob
 package/mariadb/S97mysqld Indent Shellcheck Variables
+package/matchbox-keyboard/mb-applet-kbd-wrapper.sh Shellcheck TrailingSpace
 package/mender-connect/S43mender-connect Shellcheck
 package/mii-diag/0001-strchr.patch Sob
 package/minidlna/S60minidlnad Indent Shellcheck Variables
@@ -111,6 +123,7 @@ package/netcat/0001-signed-bit-counting.patch Sob
 package/netopeer2/S52netopeer2 Shellcheck Variables
 package/netplug/0001-makefile-flags.patch Sob
 package/netplug/S29netplug Indent Shellcheck Variables
+package/netplug/netplug-script ConsecutiveEmptyLines Shellcheck
 package/netsnmp/S59snmpd Indent Shellcheck Variables
 package/network-manager/S45network-manager ConsecutiveEmptyLines EmptyLastLine Shellcheck Variables
 package/nfs-utils/S60nfs ConsecutiveEmptyLines Shellcheck Variables
@@ -122,11 +135,13 @@ package/ofono/S46ofono Variables
 package/olsr/S50olsr Indent Shellcheck Variables
 package/openntpd/S49ntp Shellcheck Variables
 package/openssh/S50sshd EmptyLastLine Indent Variables
+package/openvmtools/shutdown Shellcheck
 package/openvpn/S60openvpn Indent Shellcheck Variables
 package/oracle-mysql/S97mysqld Shellcheck Variables
 package/owfs/S55owserver Shellcheck Variables
 package/owfs/S60owfs Shellcheck Variables
 package/pigpio/S50pigpio Shellcheck Variables
+package/pkgconf/pkg-config.in Shellcheck
 package/poco/0001-Fix-optional-JSON-support-for-MySQL-3753.patch Sob
 package/postgresql/S50postgresql Variables
 package/procps-ng/S02sysctl Variables
@@ -147,6 +162,7 @@ package/samba4/S91smb Indent Shellcheck Variables
 package/seatd/S70seatd NotExecutable Variables
 package/ser2net/S50ser2net Indent Shellcheck Variables
 package/shairport-sync/S99shairport-sync Indent Shellcheck Variables
+package/skeleton-init-systemd/fakeroot_tmpfiles.sh Shellcheck
 package/smcroute/S41smcroute Indent NotExecutable Variables
 package/smstools3/S50smsd Shellcheck Variables
 package/solarus/0002-Add-a-basic-FindOpenGLES2.cmake.patch Sob
@@ -156,11 +172,13 @@ package/sslh/S35sslh Indent Shellcheck Variables
 package/stunnel/S50stunnel Indent Shellcheck Variables
 package/supervisor/S99supervisord Variables
 package/suricata/S99suricata Shellcheck
+package/swupdate/swupdate.sh Shellcheck
 package/sysrepo/S51sysrepo-plugind Indent Shellcheck
 package/targetcli-fb/S50target Shellcheck Variables
 package/tcf-agent/S55tcf-agent Shellcheck Variables
 package/tftpd/S80tftpd-hpa Indent Shellcheck Variables
 package/ti-gfx/S80ti-gfx Shellcheck Variables
+package/ti-gfx/esrev.sh Shellcheck
 package/ti-sgx-um/S80ti-sgx Variables
 package/tpm2-abrmd/S80tpm2-abrmd Indent Shellcheck Variables
 package/transmission/S92transmission ConsecutiveEmptyLines Indent Shellcheck Variables
@@ -170,10 +188,13 @@ package/unbound/S70unbound Shellcheck
 package/unscd/S46unscd Indent Shellcheck Variables
 package/upmpdcli/S99upmpdcli Indent Shellcheck Variables
 package/usbguard/S20usbguard Indent Shellcheck Variables
+package/vala/vala-wrapper Shellcheck
 package/vsftpd/S70vsftpd Indent Shellcheck Variables
 package/watchdogd/S01watchdogd Indent NotExecutable
+package/wpa_supplicant/ifupdown.sh Shellcheck
 package/x11r7/xapp_xdm/S99xdm Indent Variables
 package/x11r7/xdriver_xf86-video-mach64/0001-cross-compile.patch Sob
 package/x11r7/xdriver_xf86-video-savage/0001-cross-compile.patch Sob
 package/x11r7/xdriver_xf86-video-tdfx/0001-cross.patch Sob
 package/x11r7/xserver_xorg-server/S40xorg Shellcheck Variables
+package/xl2tp/xl2tpd TrailingSpace