Reasonably safe changes.

Using accessor for vertexbuffer in LLFace
Extra occlusion query lookup in llgl (unused)
Const changes.

indra/llmessage/lltemplatemessagereader.cpp

@@ -36,6 +36,7 @@
 #include "llfasttimer.h"
 #include "llmessagebuilder.h"
 #include "llmessagetemplate.h"
+#include "llmath.h"
 #include "llquaternion.h"
 #include "message.h"
 #include "u64.h"