rw_lock_held

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

Hi,

Is there any reason that rw_lock_held checks if it's held
by *someone*, not by curlwp? It's confusable and most (or all?)
users of the API seem to expect the latter (held by curlwp).

Well, rwlock.9 says that rw_*_held behave so, but that's perhaps
just out-of-date because rw_read_held and rw_write_held check
if it's held by curlwp.

So I think we should do either:
(1) fix rw_lock_held, or
    - probably it would be rw_read_held() || rw_write_held()
(2) fix users of rw_lock_held.
    - it also would replace rw_lock_held with
      rw_read_held() || rw_write_held()

I prefer (1) because I think there is no user of the current
behavior that is difficult to use for users (it may be useful
as an internal utility function though).

Any thoughts?

  ozaki-r