VFS: Allow caller to determine if BSD or posix locks were actually freed

Change posix_lock_file_conf(), and flock_lock_file() so that if called
with an F_UNLCK argument, and the FL_EXISTS flag they will indicate
whether or not any locks were actually freed by returning 0 or -ENOENT.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --cc fs/locks.c
Simple merge

diff --cc include/linux/fs.h
Simple merge