Older versions of gcc have problems with in-line forward declarations
when there's a naming conflict with a global symbol.
Signed-off-by: AJ Lewis <aj.lewis@quantum.com>

Expand the original patch to all such forward declarations.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Reaper thread destroys the socket asynchronously.
zmq_term() can be interrupted by a signal (EINTR).
zmq_socket() will return ETERM after zmq_term() was called.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

For historical reasons queue to transfer commands between
threads was called 'signaler'. Given that it was used to
pass commands rather than signals it was renamed to 'mailbox',
see Erlang mailboxes.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Threads were so far identified by integers called 'slots'.
This patch renames them to more comprehensible 'tid's (thread IDs).
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Sockets may now be migrated between OS threads; sockets may not be used by
more than one thread at any time. To migrate a socket to another thread the
caller must ensure that a full memory barrier is called before using the
socket from the target thread.

The new zmq_close() semantics implement the behaviour discussed at:

http://lists.zeromq.org/pipermail/zeromq-dev/2010-July/004244.html

Specifically, zmq_close() is now deterministic and while it still returns
immediately, it does not discard any data that may still be queued for
sending. Further, zmq_term() will now block until all outstanding data has
been sent.

TODO: Many bugs have been introduced, needs testing. Further, SO_LINGER or
an equivalent mechanism (possibly a configurable timeout to zmq_term())
needs to be implemented.