libext2fs: avoid pointless EA block allocation

libext2fs: avoid pointless EA block allocation

Use qsort to move the inlinedata attribute to the front of the list
and the empty entries to the end.  Then we can use handle->count to
decide if we're done writing xattrs, which helps us to avoid the
situation where we're midway through the attribute list, so we
allocate an EA block to store more, but have no idea that there's
actually nothing left in the list.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>