fix enum type generation, avoid padding issues

src/code/type.m4

@@ -117,9 +117,9 @@ define(`enum_constant',
 # enum_type_decl(T,e1,... en)                                     #
 
 define(`enum_type_decl', `
-typedef enum {
+enum type_name($1) : long {
   enum_constant(shift($@))
-} type_name($1);
+};
 
 extern const char* if_$1_name[];