raitonal.c: remove needless macro

* rational.c (id_lshift, f_lshift): removed.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56753 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

rational.c

@@ -2039,9 +2039,6 @@ float_decode(VALUE self)
 }
 #endif
 
-#define id_lshift rb_intern("<<")
-#define f_lshift(x,n) rb_funcall((x), id_lshift, 1, (n))
-
 /*
  * call-seq:
  *    flt.to_r  ->  rational