glsl/parser: Return the glsl_type object from the lexer

glsl/parser: Return the glsl_type object from the lexer

This allows us to use a single token for every built-in type except void.

   text	   data	    bss	    dec	    hex	filename
8275163	 269336	 294072	8838571	 86ddab	32-bit i965_dri.so before
8255243	 268856	 294072	8818171	 868dfb	32-bit i965_dri.so after
7836963	 346552	 420592	8604107	 8349cb	64-bit i965_dri.so before
7815195	 345592	 420592	8581379	 82f103	64-bit i965_dri.so after

Yes, the 64-bit binary shrinks by 21k.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>