Remove the custom bug fix for SDL_x11opengl.c as SDL has fixed it.

Source/ThirdParty/SDL/src/video/x11/SDL_x11opengl.c

@@ -18,9 +18,6 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
-
-// Modified by Yao Wei Tjong for Urho3D
-
 #include "../../SDL_internal.h"
 
 #if SDL_VIDEO_DRIVER_X11
@@ -777,8 +774,6 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
                         X11_XFree(framebuffer_config);
                     }
                 }
-                // Urho3D - fix memory leak detected by Valgrind
-                X11_XFree(framebuffer_config);
             }
         }
         X11_XFree(vinfo);