mie: ctx is now used to query the type of a value

this allows value get_type callbacks to use mie_ctx to obtain mie_type pointers,
rather than having to define their own static versions of the type structs.

mie/func.c

@@ -108,7 +108,7 @@ struct mie_block *mie_func_get_last_block(struct mie_func *func)
 	return (struct mie_block *)b_unbox(struct mie_value, entry, v_entry);
 }
 
-static struct mie_type *get_type(struct mie_value *v)
+static struct mie_type *get_type(struct mie_value *v, struct mie_ctx *ctx)
 {
 	struct mie_func *f = MIE_FUNC(v);
 	return f->f_ret;