MAINT-2090 Never enable lighting and shadows by default on OS X

indra/newview/llfeaturemanager.cpp

@@ -499,6 +499,10 @@ void LLFeatureManager::parseGPUTable(std::string filename)
 	{
 		LL_WARNS("RenderInit") << "GPU '" << rawRenderer << "' not recognized" << LL_ENDL;
 	}
+
+#if LL_DARWIN // never go over "Mid" settings by default on OS X
+	mGPUClass = llmin(mGPUClass, 2);
+#endif
 }
 
 // responder saves table into file