Evas GL: Fix gl_x11/GLX engine

Forgot to set the TLS value after creating a new context.
No problem would show up in most cases, even in my test app.
But elementary_test GLView would just not work at all, spitting
incomplete FBO errors at me. Damn this one line was hard to find.

But introduced in df66916cd22ec6c4.

src/modules/evas/engines/gl_x11/evas_x_main.c

@@ -293,6 +293,7 @@ eng_window_new(Evas_Engine_Info_GL_X11 *info,
         else
           context = glXCreateContext(gw->disp, gw->visualinfo, NULL, GL_TRUE);
 #endif
+        _tls_context_set(context);
      }
 #ifdef NEWGL
    rgbactx = _tls_rgba_context_get();