Bug 888 / Bug 891- Enhance GLCapabilities-Query: Add perf. test case

Even though the test case itself cannot show the proper initialization time,
it can be used w/ an attached profiler i.e.

    Test w/ 50 X11GLXGraphicsConfigurationFactory.chooseGraphicsConfigurationFBConfig() invocations:
      - pre change:  1.708 ms
      - post change:   650 ms  (613e33ee8ffc1f2b9c5db1e1b5bb5253a159ed6d)