tools/squashfs4: backport OpenWrt extended options patch

tools/squashfs4: backport OpenWrt extended options patch

Due to us keeping a patch around for years and never proposing it to
squashfs4 repository, we resulted in having the same squashfs4 version
but with different supported options. (openwrt patched -- upstream)

To workaround this problem, a non-standard option was required.

To not have surprise on tool bump, backport the patch and add the new
config option required to enable these extended non-standard options.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>