glsl: clean up textureSize prototype
glsl: clean up textureSize prototype

Signed-off-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>
Reviewed-by: Timothy Arceri <7f85c8176b2576ffafd04ac63cd29ed35ff86cb6@yahoo.com.au>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler