glsl: Delete linker stuff relating to built-in functions.

glsl: Delete linker stuff relating to built-in functions.

Now that we generate built-in functions inline, there's no need to link
against the built-in shader, and no built-in prototypes to consider.

This lets us delete a bunch of code.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by; Ian Romanick <ian.d.romanick@intel.com>