LU-13274 uapi: make lustre UAPI headers pass CONFIG_UAPI_HEADER_TEST

LU-13274 uapi: make lustre UAPI headers pass CONFIG_UAPI_HEADER_TEST

The linux kernel offers a CONFIG_UAPI_HEADER_TEST that test
if the UAPI headers can be built stand alone. Running this
kernel option against the latest lustre UAPI headers expose
some few issues still left. This patch makes everything
compliant with this kernel option which should cover potential
build issues with userland applications. A few kernel-only
bits of code have been moved to the kernel headers where they
belong.

Change-Id: I1b287c8226dd1085080218fb92e7b31b32f36b07
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38215
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Gian-Carlo DeFazio <defazio1@llnl.gov>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>