[CIFS] Add posix (advisory) byte range locking support to cifs client

Samba (version 3) server support for this is also currently being
done.  This client code is in an experimental path (requires enabling
/proc/fs/cifs/Experimental) while it is being tested.

Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --cc fs/cifs/CHANGES
Simple merge

diff --cc fs/cifs/cifspdu.h
Simple merge

diff --cc fs/cifs/cifsproto.h
Simple merge

diff --cc fs/cifs/cifssmb.c
Simple merge

diff --cc fs/cifs/file.c
Simple merge