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/convert/convert.c

@@ -6,7 +6,7 @@
 #include <string.h>
 
 struct mie_ir_converter *mie_ir_converter_create(
-	enum mie_ir_format src, enum mie_ir_format dest)
+	struct mie_ctx *ctx, enum mie_ir_format src, enum mie_ir_format dest)
 {
 	if (src == dest) {
 		return NULL;
@@ -19,6 +19,7 @@ struct mie_ir_converter *mie_ir_converter_create(
 
 	memset(out, 0x0, sizeof *out);
 
+	out->c_ctx = ctx;
 	out->c_src_format = src;
 	out->c_dest_format = dest;