internal.h: shortcut macros

* internal.h (RRATIONAL_SET_{NUM,DEN}): shortcut macros for
  internal only.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53887 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

internal.h

@@ -390,6 +390,8 @@ struct RRational {
 };
 
 #define RRATIONAL(obj) (R_CAST(RRational)(obj))
+#define RRATIONAL_SET_NUM(rat, n) RB_OBJ_WRITE((rat), &((struct RRational *)(rat))->num,(n))
+#define RRATIONAL_SET_DEN(rat, d) RB_OBJ_WRITE((rat), &((struct RRational *)(rat))->den,(d))
 
 struct RFloat {
     struct RBasic basic;