metadata.json contains 'force_glsl' but not 'glsl'.  I guess it must
have gotten renamed at some point.  Fixes the following traceback when
attempting to call 'piglit resume':

Traceback (most recent call last):
  File "/home/kayden/Projects/piglit/piglit", line 178, in <module>
    main()
  File "/home/kayden/Projects/piglit/piglit", line 174, in main
    sys.exit(runner(args))
  File "/home/kayden/Projects/piglit/framework/exceptions.py", line 52, in _inner
    func(*args, **kwargs)
  File "/home/kayden/Projects/piglit/framework/programs/run.py", line 439, in resume
    options.OPTIONS.force_glsl = results.options['glsl']

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>