LU-12355 llite: totalram_pages changed to atomic_long_t

LU-12355 llite: totalram_pages changed to atomic_long_t

Kernel 5.0 changed totalram_pages to atomic_long_t
Provide an abstracted accessor now that totalram_pages
is now a function

Conflicts:
	libcfs/autoconf/lustre-libcfs.m4
	libcfs/include/libcfs/libcfs.h
	lustre/llite/lproc_llite.c

Lustre-commit: 5ca5b19e8efdfede8ec3405eaced7202984f396b
Lustre-change: https://review.whamcloud.com/35025

Linux-commit: ca79b0c211af63fa3276f0e3fd7dd9ada2439839

Test-Parameters: trivial
Change-Id: I558e42074004e2ee5f79deea0d363e5bea332729
Signed-off-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-on: https://review.whamcloud.com/40376
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>