Reasonably safe changes.

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

indra/llmessage/llsdmessagebuilder.cpp

@@ -35,6 +35,7 @@
 #include "llsdmessagebuilder.h"
 
 #include "llmessagetemplate.h"
+#include "llmath.h"
 #include "llquaternion.h"
 #include "llsdutil.h"
 #include "llsdutil_math.h"