iseq.h: fix argument order

* iseq.h (ISEQ_ORIGINAL_ISEQ_ALLOC): the order of ruby_xmalloc2
  arguments is `count` and `element size`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63380 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

iseq.h

@@ -63,7 +63,7 @@ static inline VALUE *
 ISEQ_ORIGINAL_ISEQ_ALLOC(const rb_iseq_t *iseq, long size)
 {
     return iseq->body->variable.original_iseq =
-        ruby_xmalloc2(sizeof(VALUE), size);
+        ruby_xmalloc2(size, sizeof(VALUE));
 }
 
 #define ISEQ_TRACE_EVENTS (RUBY_EVENT_LINE  | \