LU-10752 build: fix rpm packaging issues for gss

LU-10752 build: fix rpm packaging issues for gss

Lustre can create rpms in two ways. One is with make rpm and the
other is using the actual source rpm that is provided. Their are
several issues with how GSS is handled with rpm packaging.

First problem is that you can ./configure --disable-gss which has
never been handled. Secondly if you do configure with disable-gss
it is still possible to have the option enable-gss-keyring set to
yes. The reason it was never seen before is due to everything
being treated with the keyring option. Now if the user sets
enable-gss to no then enable-gss-keyring will also be set to no
even if the user tries to set it to yes. This was done by properly
setting $enable_gss and $enable_gss_keyring in lustre-core.m4.
In the spec file create the bcond gss to handle the gss only case
and we turn on gss if gss_keyring is true. Move lgssc.conf under
the with_gss_keyring bcond which is only needed for server builds
along side lsvcgss.

It is impossible to know if it can build due to the spec file not
properly handling build dependencies for GSS and not knowing if
the kernel is too new for GSS. So the user has to provide the
options --with gss and / or --with gss-keyring to rpmbuild. If
the user only provides gss-keyring option to rpmbuild make sure
it enables gss as well. That is handled in the spec file.

For the case of make rpms fix it up so if gss-keyring is enabled
then by default the core gss handling is enabled. Also handle the
long ignored enable-gss case.

Test-Parameters: trivial

Change-Id: Ieed9df98a27bd6e77504486762d6e60ddca5a916
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/31757
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Elena Gryaznova <c17455@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>