RM-844 lbuild: add support for building kmod-lustre-o2ib-ofed

RM-844 lbuild: add support for building kmod-lustre-o2ib-ofed

With this patch, we will be able to build ofed
and mlnx lustre RPMS at the same time.

Introduce extra option --enable-o2ib_kernel
to lbuild enable ofed RPMS, in default, it won't be built.

This is a quick walkaround solution that we could
support both MLNX and OFED KMOD RPMS, for the long
term, we should handle this more gracefully

Test-Parameters: trivial
Change-Id: I581535d2e13b5d412a9b6e057294eb146f4ef086
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/41875
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>