anv/meta_blit: Coalesce glsl_vec4_type vars
anv/meta_blit: Coalesce glsl_vec4_type vars

Just a refactor. No behavior change.

Several expressions have the same value: they point to
glsl_vec4_type(). Coalesce them into a single variable.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler