[Piglit] [PATCH] arb_shading_language_420pack: Make compatible with 4.30.

[Pohjolainen, Topi]

On Mon, Jun 06, 2016 at 02:40:15PM -0700, Matt Turner wrote:
> 4.30 removes gl_FragColor. In debugging bug 96320, I found it useful to
> replace gl_FragColor with a user-defined varying so that the tests could
> be run under GLSL 4.30.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>