In the past, it has been useful to enable PROVE_LOCKING without also
enabling PROVE_RCU.  However, experience with PROVE_RCU over the past
few years has demonstrated its usefulness, so this commit makes
PROVE_LOCKING directly imply PROVE_RCU.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>