compiler/types: Use designated initializer syntax to specify builtins

compiler/types: Use designated initializer syntax to specify builtins

For now we use a temporary glsl_type_params struct, we will be able to
use the glsl_type directly once we make it a POD ("plain old data")
struct by getting rid of its constructors and destructors.

Note that since the name is statically allocated, there's no need to
strdup() it, deallocate it and also no need to have a mem_ctx.

Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25006>