glsl/glcpp: Rename one test to avoid a duplicate test number

glsl/glcpp: Rename one test to avoid a duplicate test number

With two tests both numbered 118, there was a confusing off-by-two difference
between the last test number and the total number of tests (as reported by
glcpp-test).

With this rename, there's only an off-by-one difference left, (which is easy
to understand given the zero-based test numbering).

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>