LU-4606 utils: Mount uses so for backing fstype

Make mount/mkfs/tunefs functionality a per backing FSTYPE shared
object that is loadable, and seperately buildable and installable
in the appropriate lustre-osd-FSTYPE rpm.

For ZFS this allows the shared object to be directly linked to libzfs
and thus remove the hardcoding of a libzfs.so version in the lustre
source. This also has the benefit of making lustre-osd-zfs explicitly
requires libzfs (which it needs to do mount/mkfs operations).

Adjust build system to allow building of loadable module.  Including
requiering libtool as part of the build.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I8fc0f41161dc08405c1f951f12e675f364ff62c3
Reviewed-on: http://review.whamcloud.com/10193
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>