numeric.c: fix typo

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65680 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

numeric.c

@@ -1109,7 +1109,7 @@ rb_flo_div_flo(VALUE x, VALUE y)
 {
     double num = RFLOAT_VALUE(x);
     double den = RFLOAT_VALUE(y);
-    double ret = double_div_double(x, y);
+    double ret = double_div_double(num, den);
     return DBL2NUM(ret);
 }