Fix typo in OGLRenderSurface.cpp

Source/Urho3D/Graphics/OpenGL/OGLRenderSurface.cpp

@@ -103,7 +103,7 @@ void RenderSurface::OnDeviceLost()
     // Clean up also from non-active FBOs
     graphics->CleanupRenderSurface(this);
 
-    if (renderBuffer_ && !graphics_->IsDeviceLost())
+    if (renderBuffer_ && !graphics->IsDeviceLost())
         glDeleteRenderbuffersEXT(1, &renderBuffer_);
 
     renderBuffer_ = 0;