This patch adds tests for the following built-in GLSL operators:

- op-add, op-sub, op-mult, op-div: binary arithemetic operators on
  floats, vecs, mats, ints, and ivecs.

- op-uplus, op-neg: unary arithmetic operators on floats, vecs, mats,
  ints, and ivecs.

- op-gt, op-lt, op-ge, op-le: comparison operators on ints and floats.

- op-eq, op-ne: equality and inequality comparison on any GLSL 1.20 type.

- op-and, op-or, op-xor: logical operations on bools.

- op-not: unary logical not on bools.

- op-selection: trinary selection operator (x?y:z), where the first
  argument is a bool and the second and third arguments are any GLSL
  1.20 type.

Note that implicit type conversions are not tested.  So, for instance,
int * ivec is tested, but float * ivec is not.  This was in an effort
to avoid generating an outrageous number of tests.

Note also that the "shortcut" behavior of logical and/or and trinary
selection is not tested.

These tests leverage the same test generation framework used to test
built-in functions, so the tests exercise vertex shaders, fragment
shaders, and constant folding.

All in all 1332 tests are added, in the subtrees
spec/glsl-1.{10,20}/{compiler,execution}/built-in-functions.

Reviewed-by: Eric Anholt <eric@anholt.net>