Regression test portability: stat

Improve BSD compatibility for stat. The new version attemps to spawn
less stat subprocesses.

Also add translation for %X %Y and %Z

BUG: 1129939
Change-Id: I2b2134f9e8336a952aee6c7679ba0491abd5a35c
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/8565
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Harshavardhana <harsha@harshavardhana.net>
Tested-by: Harshavardhana <harsha@harshavardhana.net>