Pulled SSAO out into its own shader to support running at a lower-than-native framebuffer resolution (defaults at half-resolution [SHRenderSSAOResolutionScale=.5] ). This doesn't improve the slow ssao/shadow softening, however, as that bit remains unchanged.

indra/newview/pipeline.h

@@ -615,6 +615,7 @@ public:
 	LLRenderTarget			mFXAABuffer;
 	LLRenderTarget			mEdgeMap;
 	LLRenderTarget			mDeferredDepth;
+	LLRenderTarget			mDeferredDownsampledDepth;
 	LLRenderTarget			mOcclusionDepth;
 	LLRenderTarget			mDeferredLight;
 	LLMultisampleBuffer		mSampleBuffer;