QueuingRWLock: Resolve a final compiler warning.
QueuingRWLock: Resolve a final compiler warning.

Technically, some of these volatiles shouldn't be necessary; any
compiler warnings should be eliminatd with casts.  However, 1) at
worse they add some extra memory loads; and 2) back in June 09, at
least one of them appeared to be necessary for GCC 4.1.2 to generate
correct code.  This should be revisited -- possibly there was another
explanation.


zcth428/hpctoolkit,zcth428/hpctoolkit,HPCToolkit/hpctoolkit,zcth428/hpctoolkit111,zcth428/hpctoolkit111,HPCToolkit/hpctoolkit,zcth428/hpctoolkit,zcth428/hpctoolkit111,zcth428/hpctoolkit111,zcth428/hpctoolkit111,zcth428/hpctoolkit,HPCToolkit/hpctoolkit,zcth428/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit