glsl: Convert varying test to the util hash table
glsl: Convert varying test to the util hash table

V2: remove now unused ht_count_callback() (Timothy Arceri)

Signed-off-by: Thomas Helland <ca565e508460f734dd9d29a6ab6bd7e0e3ccde1d@gmail.com>
Reviewed-by: Timothy Arceri <5dd83789ef3714029244367ba1ca09f1d7627408@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler