LU-1199 build: Clean out the build directory

LU-1199 build: Clean out the build directory

Clean up the build directory.  Move in the direction of reserving
"build/" for the special-purpose Makefile that lives there.
Eventually we could rewrite the autoconf tests to eliminate that
Makfile, and the build directory could disappear altogether (after
finding homes for anything else that is left).

The autoconf m4 file move into a top level "config" directory.

Most other things that have moved are put in the new "contrib"
top-level directory.  For instance, "contrib/lbuild" contains
all of the lbuild-related files, and "contrib/git-hooks" contains
the git hooks for lustre developers.

Most of the moved files were unchanged, however the lbuild scripts
needed some tweaking to deal with the new location.

Because of the way that Intel's build farm and git hooks expect to
find certain files in fixed locations I have had to leave a few
symlinks in place that point to the new locations.

Change-Id: I04dc529d4f4060b892e1e4eaa8613bbc3337c414
Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Reviewed-on: http://review.whamcloud.com/5035
Reviewed-by: Brian J. Murrell <brian.murrell@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>