OpenGL: Check the list of supported AA modes instead of hardcoding

Source/Core/VideoBackends/OGL/OGLMain.cpp

@@ -142,7 +142,7 @@ bool VideoBackend::FillBackendInfo(GLContext* context)
   g_Config.backend_info.bSupportsGPUTextureDecoding = true;
   g_Config.backend_info.bSupportsBBox = true;
 
-  // Overwritten in OGLRender.cpp later
+  // Overwritten in OGLConfig.cpp later
   g_Config.backend_info.bSupportsDualSourceBlend = true;
   g_Config.backend_info.bSupportsPrimitiveRestart = true;
   g_Config.backend_info.bSupportsPaletteConversion = true;
@@ -182,6 +182,13 @@ bool VideoBackend::FillBackendInfo(GLContext* context)
     return false;
   }
 
+  if (!PopulateConfig(context))
+  {
+    // Not all needed extensions are supported, so we have to stop here.
+    // Else some of the next calls might crash.
+    return false;
+  }
+
   // TODO: Move the remaining fields from the Renderer constructor here.
   return true;
 }