mesa: Replace uses of Shared->Mutex with hash-table mutexes

mesa: Replace uses of Shared->Mutex with hash-table mutexes

We were locking the Shared->Mutex and then using calling functions like
_mesa_HashInsert that do additional per-hash-table locking internally.

Instead just lock each hash-table's mutex and use functions like
_mesa_HashInsertLocked and the new _mesa_HashRemoveLocked.

In order to do this, we need to remove the locking from
_mesa_HashFindFreeKeyBlock since it will always be called with the
per-hash-table lock taken.

Reviewed-by: Timothy Arceri <t_arceri@yahoo.com.au>
Reviewed-by: Brian Paul <brianp@vmware.com>