Support mutli-arch disks by specifying the arch

Specify the arch on the command line and mountpoints
so that we can support mutli-arch livecds

Signed-off-by: Aaron Griffin <aaronmgriffin@gmail.com>

archiso/hooks/archiso

@@ -27,6 +27,10 @@ _mnt_squashfs()
 
 run_hook ()
 {
+    if [ "x${arch}" = "x" ]; then
+        arch="$(uname -m)"
+    fi
+
     if [ "x${ramdisk_size}" = "x" ]; then
         ramdisk_size="75%"
     fi
@@ -100,10 +104,12 @@ run_hook ()
     export LOOP_NUM="0"
     if [ -e "/mounts" ]; then
         msg ":: Mounting images"
-        while read img mountpoint type; do
+        while read img imgarch mountpoint type; do
             # check if this line is a comment (starts with #)
             [ "${img#"#"}" != "${img}" ] && continue
 
+            [ "$imgarch" != "$arch" ] && continue
+
             if [ "${type}" = "bind" ]; then
                 _mnt_bind ${img} ${mountpoint}
             elif [ "${type}" = "squashfs" ]; then