This change adds ANGLE support for following vector relational
function variants introduced in GLES3:
bvec lessThan(uvec x, uvec y)
bvec lessThanEqual(uvec x, uvec y)
bvec greaterThan(uvec x, uvec y)
bvec greaterThanEqual(uvec x, uvec y)
bvec equal(uvec x, uvec y)
bvec notEqual(uvec x, uvec y)

BUG=angle:920
TEST=dEQP tests
Reduced number of errors in tests:
dEQP-GLES3.functional.shaders.constant_expressions.builtin_functions.vector_relational.*

Change-Id: Id45ce77b35f39403e587a577622271d8e9815225
Reviewed-on: https://chromium-review.googlesource.com/250377Reviewed-by: Nicolas Capens <capn@chromium.org>
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>