LU-3389 build: Fix build fails on RHEL6.4 kernel with OFED-3.5

OFED-3.5.1 supports RHEL6.4 kernel. CONFIG_COMPAT_RHEL_6_4 macro
needs to build lustre with them.

backport from http://review.whamcloud.com/6448

Signed-off-by: Shuichi Ihara <sihara@ddn.com>
Change-Id: Ib082bdf08d9a4b609178ff572cae677699d988fe
Reviewed-on: http://review.whamcloud.com/7216
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>