package/ngrep: fix build with libnet

Use pkg-config to find libnet and avoid the following build failure
raised since commit 100ba8351c if
libnet-config is found on the host:

/home/autobuild/autobuild/instance-4/output-1/host/bin/mips64el-buildroot-linux-gnu-gcc -s -o ngrep ngrep.o  tcpkill.o   -lpcap -lnet   -lpcre -L/usr/lib -lnet
mips64el-buildroot-linux-gnu-gcc: ERROR: unsafe header/library path used in cross-compilation: '-L/usr/lib'

While at it, format Upstream tag of other patches

Fixes:
 - http://autobuild.buildroot.org/results/05c916162b9c1027cf53f1699a1f5653151098ed

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 14c0c37eaf)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/ngrep/0001-Fix-typo-in-configure-in-when-testing-for-use_pcre.patch

@@ -4,8 +4,7 @@ Date: Mon, 1 Jan 2018 18:00:34 +0100
 Subject: [PATCH] Fix typo in configure.in when testing for use_pcre
 
 Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
-[Retrieved from:
-https://github.com/jpr5/ngrep/commit/b8b1e9751e1d074af0dd77c2554c1b25fd8f7abe]
+Upstream: https://github.com/jpr5/ngrep/commit/b8b1e9751e1d074af0dd77c2554c1b25fd8f7abe
 ---
  configure.in | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

package/ngrep/0002-Check-for-libnet_init-in-configure-in.patch

@@ -7,8 +7,7 @@ libnet_init_packet was the old libnet 1.0 function which is now long
 deprecated.
 
 Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
-[Retrieved from:
-https://github.com/jpr5/ngrep/commit/0a51c8bc62c7b49b8d67a360daa6b1957256f4f5]
+Upstream: https://github.com/jpr5/ngrep/commit/0a51c8bc62c7b49b8d67a360daa6b1957256f4f5
 ---
  configure.in | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

package/ngrep/0003-fix-disable-tcpkill.patch

@@ -9,7 +9,7 @@ found on the system.
 To fix this, move AC_CHECK_LIB to found libnet outside AC_ARG_ENABLE
 
 Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
-[Upstream status: https://github.com/jpr5/ngrep/pull/15]
+Upstream: https://github.com/jpr5/ngrep/pull/15
 ---
  configure.in | 6 ++----
  1 file changed, 2 insertions(+), 4 deletions(-)

package/ngrep/0004-configure.in-use-pkg-config-to-find-libnet.patch

@@ -0,0 +1,38 @@
+From 4788988827bf4c0d996d3e1e3b6ac52a23b97941 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Tue, 9 Jan 2024 21:15:47 +0100
+Subject: [PATCH] configure.in: use pkg-config to find libnet
+
+libnet-config is deprecated:
+https://github.com/libnet/libnet/commit/1ec4a6e7d1d23811f0a14ecb51e46489a0175727
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Upstream: unsent (upstream seems dead, no commit since 5 years
+---
+ configure.in | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/configure.in b/configure.in
+index 7c3dd43..882ff86 100644
+--- a/configure.in
++++ b/configure.in
+@@ -176,12 +176,14 @@ AC_ARG_ENABLE(tcpkill,
+ [ use_tcpkill="$enableval" ],
+ [ use_tcpkill="no" ])
+ 
++PKG_PROG_PKG_CONFIG
+ if test $use_tcpkill = yes; then
+   AC_CHECK_LIB(net, libnet_init,,echo !!! error: tcpkill feature enabled but no libnet found; exit)
+   USE_TCPKILL="1"
+   EXTRA_OBJS="$EXTRA_OBJS tcpkill.o"
+-  EXTRA_DEFINES="$EXTRA_DEFINES $(libnet-config --defines)"
+-  EXTRA_LIBS="$EXTRA_LIBS $(libnet-config --libs)"
++  PKG_CHECK_MODULES(LIBNET, libnet)
++  EXTRA_DEFINES="$EXTRA_DEFINES $LIBNET_CFLAGS"
++  EXTRA_LIBS="$EXTRA_LIBS $LIBNET_LIBS"
+ else
+   USE_TCPKILL="0"
+ fi
+-- 
+2.43.0
+

package/ngrep/ngrep.mk

@@ -22,7 +22,7 @@ NGREP_CONF_OPTS = \
 	--disable-dropprivs \
 	--disable-pcap-restart
 
-NGREP_DEPENDENCIES = libpcap pcre
+NGREP_DEPENDENCIES = host-pkgconf libpcap pcre
 
 ifeq ($(BR2_PACKAGE_LIBNET),y)
 NGREP_DEPENDENCIES += libnet