hash.c: remove repeated rb_hash_start

* hash.c (rb_dbl_long_hash): remove repeated rb_hash_start as
  rb_objid_hash includes rb_hash_start,

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66942 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

hash.c

@@ -159,7 +159,7 @@ rb_dbl_long_hash(double d)
 	union {double d; uint64_t i;} u;
 
 	u.d = d;
-	return rb_objid_hash(rb_hash_start(u.i));
+	return rb_objid_hash(u.i);
     }
 #endif
 }