init-install*: /etc/mtab make a link rather than a copy

Using a copy would only make management of devices erroneous
and makes the system unstable in some scenarios as tools will
have to manipulate both files separately. A link ensures that
both files /proc/mounts and /etc/mtab will have the same
information at all times and this is how it is handled
on newer systems where there is such a need. Same is
suggested by busybox.

(From OE-Core rev: 9f9240d175acee274c04242fd5781094b3f5491b)

Signed-off-by: Awais Belal <awais_belal@mentor.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/initrdscripts/files/init-install-efi.sh

@@ -128,8 +128,8 @@ umount ${device}* 2> /dev/null || /bin/true
 mkdir -p /tmp
 
 # Create /etc/mtab if not present
-if [ ! -e /etc/mtab ]; then
-    cat /proc/mounts > /etc/mtab
+if [ ! -e /etc/mtab ] && [ -e /proc/mounts ]; then
+    ln -sf /proc/mounts /etc/mtab
 fi
 
 disk_size=$(parted ${device} unit mb print | grep '^Disk .*: .*MB' | cut -d" " -f 3 | sed -e "s/MB//")

meta/recipes-core/initrdscripts/files/init-install.sh

@@ -124,8 +124,8 @@ if [ ! -b /dev/loop0 ] ; then
 fi
 
 mkdir -p /tmp
-if [ ! -L /etc/mtab ]; then
-    cat /proc/mounts > /etc/mtab
+if [ ! -L /etc/mtab ] && [ -e /proc/mounts ]; then
+    ln -sf /proc/mounts /etc/mtab
 fi
 
 disk_size=$(parted ${device} unit mb print | grep '^Disk .*: .*MB' | cut -d" " -f 3 | sed -e "s/MB//")