ext4_utils: Fix FS creation for filesystems with exactly 32768 blocks.

In that case, total block count matches number of blocks per group,
which yields precisely 1 group. last_group_size in that case was
calculated as 0, which together with group count 1 incorrectly triggered
the file size check. Special case that scenario by assigning
last_group_size as 32768 in that case.

Change-Id: I3b6e236a4d6951aca732324b85e46b8c4b5757b7
1 file changed