- ar utility can vary depeding on build platform.
- do not call gcc directly, use $(CC)

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Ia60752b40531886d805a095c9f571e565bcd0e88
Reviewed-on: http://review.whamcloud.com/3917


Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Liu Xuezhao <xuezhao.liu@emc.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>