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/llrender/llshadermgr.cpp

@@ -1177,6 +1177,7 @@ void LLShaderMgr::initAttribsAndUniforms()
 	mReservedUniforms.push_back("depth_cutoff");
 	mReservedUniforms.push_back("norm_cutoff");
 	mReservedUniforms.push_back("shadow_target_width");
+	mReservedUniforms.push_back("downsampled_depth_scale");
 	
 	llassert(mReservedUniforms.size() == LLShaderMgr::DEFERRED_SHADOW_TARGET_WIDTH+1);
 
@@ -1195,6 +1196,7 @@ void LLShaderMgr::initAttribsAndUniforms()
 	mReservedUniforms.push_back("dof_height");
 
 	mReservedUniforms.push_back("depthMap");
+	mReservedUniforms.push_back("depthMapDownsampled");
 	mReservedUniforms.push_back("shadowMap0");
 	mReservedUniforms.push_back("shadowMap1");
 	mReservedUniforms.push_back("shadowMap2");