The spec allows adding scalars with a vector or matrix. In this case
the opt was losing swizzle and size information.
This fixes a bug with Doom (2016) shaders.
Fixes: 34ec1a24d6 ("glsl: Optimize (x + y cmp 0) into (x cmp -y).")
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>