LU-5969 lustreapi: replace llapi_get_version()

LU-5969 lustreapi: replace llapi_get_version()

The existing llapi_get_version() helper has an awkward calling
style, requiring a temporary input buffer, as well as an output
pointer.

Replace this with llapi_get_version_string() which returns the
the simple version string.  Mark llapi_get_version() deprecated.
Update "lctl lustre_build_version" to use llapi_version_string().

These versions are extracted from {/proc,/sys}/fs/lustre/version
instead of an ioctl, to avoid the messiness that is Lustre ioctls.

Update the "version" file to only print the "lustre:" version,
since the "build:" version is now identical, and the "kernel:"
version has been "patchless_client" for many years already.

Print out the build version at the start of each test so it is
logged in the test results for convenience.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I681a353e6f65fd1ec2d1434fe38dfa55ed3ebbe5
Reviewed-on: http://review.whamcloud.com/16721
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>