package/mke2img: set sparse_super for revision 1

The sparse_super feature is more efficient in terms of speed and
available space, so set it by default if supported, i.e. for revision 1.

This gives a huge speed gain for large resize2fs operations, especially
for expansion.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mke2img/mke2img

@@ -82,7 +82,7 @@ main() {
 
     # Upgrade to rev1 if needed
     if [ ${rev} -ge 1 ]; then
-        tune2fs_O_opts+=",filetype"
+        tune2fs_O_opts+=",filetype,sparse_super"
     fi
 
     # Add a journal for ext3 and above