glsl: add a shader info field to the gl_program type

glsl: add a shader info field to the gl_program type

And use this field as the source for shader info in the nir_shader
this will allow us to set some of these fields from GLSL directly.

It will also simplify restoring from shader cache and allow the
removal of duplicate fields from GLSL.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>