Replace all uses of the vm page queues lock by a r/w lock that is private to this pmap.c.  This new r/w lock is used primarily to synchronize access to the PV lists.  However, it will be used in a somewhat unconventional way.  As finer-grained PV list locking is added to each of the pmap functions that acquire this r/w lock, its acquisition will be changed from write to read, enabling concurrent execution of the pmap functions with finer-grained locking.
Replace all uses of the vm page queues lock by a r/w lock that is private
to this pmap.c.  This new r/w lock is used primarily to synchronize access
to the PV lists.  However, it will be used in a somewhat unconventional
way.  As finer-grained PV list locking is added to each of the pmap
functions that acquire this r/w lock, its acquisition will be changed from
write to read, enabling concurrent execution of the pmap functions with
finer-grained locking.

X-MFC after:	r236045

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase