LU-339 use new aops for kernel >= RHEL5.4

LU-339 use new aops for kernel >= RHEL5.4

Kernel in RHEL5 >= 5.4 supports both old and new aops interface,
and a flag MS_HAS_NEW_AOPS is used to mark whether a filesystem
supports new aops.
Lustre has implemented the new aops, but not enabled. And with
new aops a single thread I/O can gain 5% perf increase.

Signed-off-by: Lai Siyao <laisiyao@whamcloud.com>
Change-Id: I23bbfcd105c1ffd7f6c942342f9c1fb29a1cffe4
Reviewed-on: http://review.whamcloud.com/592
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>