xfstests: add fio requirement V2

xfstests: add fio requirement V2

FIO is very flexible io generator, I would call it IO swiss knife.
Currently we have tons of hardcoded application which reproduces
some predefined scenario. This approach has obvious disadvantages
1) Lack of flexibility: one written it is hard to modify it in future
2) Code base is large, many routines written again and again

At the same time add new fio based test, just add simple INI file.
This greatly simplifies code review. I do believe that some day we will
replace most of hardcoded io binaries with fio.

One who is planning to run $FIO_PROG should first check that system
contains appropriate version which is able to handle jobfile
for example:  _require_fio 286-job.fio

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Rich Johnston <rjohnston@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>