Reasonably safe changes.

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

indra/newview/llviewercamera.cpp

@@ -729,6 +729,10 @@ LLVector3 LLViewerCamera::roundToPixel(const LLVector3 &pos_agent)
 
 BOOL LLViewerCamera::cameraUnderWater() const
 {
+	if(!gAgent.getRegion())
+	{
+		return FALSE ;
+	}
 	return getOrigin().mV[VZ] < gAgent.getRegion()->getWaterHeight();
 }