generic/077: fall back to /usr if /lib/modules doesn't exist

We need a source of "filler" that can fill up a 50M file system.
Unfortunately, on some systems /lib/modules might not exist at all.
In that case, use /usr instead.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/077

@@ -32,6 +32,9 @@ status=1
 # Something w/ enough data to fill 50M of fs...
 filler=/lib/modules/
 
+# fall back in case /lib/modules doesn't exist
+[ -d $filler ] || filler=/usr
+
 _cleanup()
 {
 	cd /