create mtab, /lib/modules and writable mountpoints on touch and core

debian/changelog

@@ -1,3 +1,11 @@
+livecd-rootfs (2.304) UNRELEASED; urgency=medium
+
+  * -touch/-core create /etc/mtab link, /lib/modules dir and the respective
+    writable mountpoints (/userdata for touch, /writable for core) so we do
+    not need to re-pack the rootfs on the system-image server to add them.
+
+ -- Oliver Grawert <ogra@ubuntu.com>  Thu, 28 May 2015 12:17:32 +0200
+
 livecd-rootfs (2.303) wily; urgency=medium
 
   * drop grouper from touchsubarches variable. the android package does not

live-build/ubuntu-core/hooks/20-extra-files.chroot

@@ -0,0 +1,8 @@
+#! /bin/sh
+
+set -e
+
+echo "creating mtab and modules dir" >&2
+ln -sf /proc/mounts /etc/mtab
+mkdir -p /lib/modules
+mkdir -p /writable

live-build/ubuntu-touch/hooks/20-extra-files.chroot

@@ -0,0 +1,8 @@
+#! /bin/sh
+
+set -e
+
+echo "creating mtab and modules dir" >&2
+ln -sf /proc/mounts /etc/mtab
+mkdir -p /lib/modules
+mkdir -p /userdata