New top-level directory: system

This directory groups the following elements:
 * the default root filesystem skeleton
 * the default device tables
 * the Config.in options for system configuration (UART port for
   getty, system hostname, etc.)
 * the make rules to apply the system configuration options

Even though the skeleton and device tables could have lived in fs/, it
would have been strange to have the UART, system hostname and other
related options into fs/. A new system/ directory makes more sense.

As a consequence, this patch also removes target/Makefile.in, which
has become useless in the process.

[Peter: fixup TARGET_SKELETON settings / documentation to match]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Yann E. MORIN <yann.morin.1998@free.fr>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

system/skeleton/root/.bash_logout

@@ -0,0 +1,7 @@
+# ~/.bash_logout: executed by bash(1) when login shell exits.
+
+# when leaving the console clear the screen to increase privacy
+
+case "`tty`" in
+    /dev/tty[0-9]*) clear
+esac

system/skeleton/root/.bash_profile

@@ -0,0 +1,15 @@
+# .bash_profile
+
+export PATH=\
+/bin:\
+/sbin:\
+/usr/bin:\
+/usr/sbin:\
+/usr/bin/X11:\
+/usr/local/bin
+
+umask 022
+
+if [ -f ~/.bashrc ]; then
+    source ~/.bashrc
+fi