LU-1346 libcfs: remove cfs_ file wrappers

Replace file relevant wrappers with kernel API.

Affected primitives:
file, dentry, dirent, kstatfs, filp_size, filp_poff,
filp_open, do_fsync, filp_close, filp_read, filp_write,
filp_fsync, get_file, fget, fput, file_count, flock_t,
flock_type, flock_set_type, flock_pid, flock_set_pid,
flock_start, flock_set_start, flock_end, flock_set_end.

completion, init_completion, fini_completion,
wait_for_completion, complete

Change some API implementations of darwin/winnt to make it be
consistent with linux kernel API such as filp_open/filp_close etc.

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Ibe00df71c658aeb5dda854481f6ab5c181b3de7b
Reviewed-on: http://review.whamcloud.com/2830
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Peng Tao <bergwolf@gmail.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>