[Mesa-stable] Pick 9bdb5457f4ecabd59e05d0b6cea1ff88bcb49d7f

[Fabian Bieler]

commit 9bdb5457f4ecabd59e05d0b6cea1ff88bcb49d7f
Author: Fabian Bieler <fabianbieler at fastmail.fm>
Date:   Thu Nov 23 13:48:00 2017 -0700

glsl: Match order of gl_LightSourceParameters elements.

spotExponent and spotCosCutoff were swapped in the
gl_builtin_uniform_element struct. Now the order matches across
gl_builtin_uniform_element, glsl_struct_field and the spec.

Reviewed-by: Brian Paul <brianp at vmware.com>
---
Note that without this patch the values of spotExponent and
spotCosCutoff are swapped.