This requires sorting all equality functions together so that struct
equality functions can have dependencies on array equality functions, but
support for array equality functions that have dependencies on struct
equality functions is also maintained.

There's no automated test coverage for this specifically. The change was
tested by manually inspecting shader output and ensuring that there were
no test regressions in tests listed below.

TEST=dEQP-GLES3.functional.shaders.*
BUG=angleproject:954

Change-Id: If7199ab2446804afae50f103bb625101172882b9
Reviewed-on: https://chromium-review.googlesource.com/261550Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>