LU-12342 spec: mark lsvcgss as a config file in the rpm

LU-12342 spec: mark lsvcgss as a config file in the rpm

The file /etc/sysconfig/lsvcgss shouldn't be overwritten on package
upgrades.

Lustre-change: https://review.whamcloud.com/34978
Lustre-commit: cfe9e1a56c696bcbba24dd4041845ead12aba291

Signed-off-by: Götz Waschk <goetz.waschk@desy.de>
Change-Id: I3fa0a3a5a06d9e59699d23e652329365f38fd028
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35087
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>