Tweaks to stencil handling to allow masking out of sky (or geometry).

Reset stencil clear value to 0 after done clearing.

indra/newview/llspatialpartition.cpp

@@ -1528,6 +1528,7 @@ static LLFastTimer::DeclareTimer FTM_OCCLUSION_DRAW("Draw");
 
 void LLSpatialGroup::doOcclusion(LLCamera* camera)
 {
+	LLGLDisable stencil(GL_STENCIL_TEST);
 	if (mSpatialPartition->isOcclusionEnabled() && LLPipeline::sUseOcclusion > 1)
 	{
 		//static const LLCachedControl<BOOL> render_water_void_culling("RenderWaterVoidCulling", TRUE);
@@ -3867,6 +3868,8 @@ public:
 			return;
 		}
 
+		LLGLDisable stencil(GL_STENCIL_TEST);
+
 		group->rebuildGeom();
 		group->rebuildMesh();