contrib: script to create minified ext4 image from a directory

contrib: script to create minified ext4 image from a directory

The dir2fs script converts a directory into a minimized ext4 filesystem.
FS creation parameters are tweaked to reduce as much FS overhead as
possible, and to leave as few unused blocks and inodes as possible.
Given that mke2fs -d lays out files linearly from the beginning of the
FS, using resize2fs -M is not as horrible as it usually is.

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