Don't shortcut macro expansion of non-parameter macros. It won't work once we have more kinds of expansion items than strings and arguments, viz., magic tokens for __FILE__ and __LINE__ and so on. (separate version of this applied against Joerg's changes, because we need to revert some of them)

/*
comment?
*/
/* comment? */
abc /* def */ ghi
abc /* def  ghi */ jkl
/*
*/
baz