Silence all "unused parameter" warnings from Clang.

This formerly unused parameter actually represents the socket
on which the event was received. As such, we should check that
its value makes sense: it must be either "rep" or "req", and in
the case of some kinds of events, it must be specifically one
or the other.

After this change, "s" is no longer unused.

Compiling without warnings is a good goal, because it makes
new warnings (which probably indicate bugs) stand out rather
than getting lost in the spam.

My fixes fall into two categories:

    - Adding (void) casts of unused parameters, where their
      unusedness seems like a TODO (or in some cases a bug?).

    - Removing parameter names altogether, where the function
      is clearly a stub that will never use its parameters.

Should be no change in behavior.

char_traits<unsigned char>::to_char_type(x) used to return 0 no matter
what x was, and likewise to_int_type(x) used to return 0 no matter what.
(0 is what you get when you default-construct an integral type, which
is what the old code was doing.) This seemed like buggy behavior to me,
so I've changed it.

Fix build breaking typos in monitor VA code

Include a note about potential interactions with reactors, and update
reference to old FAIL_UNROUTABLE name.

The endpoint was excluding the tcp://, causing tests to fail

Code as stands breaks shutdown process. It was a bugfix by Arthur to a
bad line which was testing for an impossible state - but afaics we do
actually want to flush in those states. It is possible I am wrong on
that though - if there are any shutdown issues introduced aroudn this
commit I would suggest further investigation around this flushing
behavior.

VA specific monitor event in socket base was named monitor_event rather
than va_monitor_event

The call to the va version of the function was using 'event' instead of
'event_'

Compile was failing on the monitor_event function function due to the
va_start params being switched.

Various bugfixes found by compiling with extra warnings

There are three versions of monitor_event(), all taking
variadic arguments. The original code just has the first one
creating a va_list and passing that va_list variadically to
the second one... which creates a new va_list and passes it
variadically to the third one... and of course everything
blows up when we try to pull a non-va_list argument off the
stack.

The correct approach matches the C standard library's use
of printf/vprintf, scanf/vscanf, and so on. Once you make
a va_list, you must pass it only to functions which expect
a va_list parameter.

Static analysis says:
src\tcp_address.cpp(297): error V595: The 'res' pointer was utilized before it was verified against nullptr. Check lines: 297, 301.
src\tcp_address.cpp(603): error V106: Implicit type conversion third argument 'full_bytes' of function 'memcmp' to memsize type.
src\tcp_address.cpp(603): error V526: The 'memcmp' function returns 0 if corresponding buffers are equal. Consider examining the condition for mistakes.

In fact the use of "memcmp" is correct, but the enclosing "if" isn't
necessary, and the compiler is happier if "full_bytes" is a size_t.

Static analysis says:
src\pipe.cpp(193): error V547: Expression is always false. Probably the '||' operator should be used here.

If flush() is called on a pipe whose state was
"terminated" or "double_terminated", the programmer's
intent was to return immediately. But in fact the
two conditions can never be true simultaneously, so
the early return never happens, and we may try to flush
a terminated pipe anyway.

Static analysis says:
src\fd.hpp(38): error V103: Implicit type conversion from memsize to 32-bit type.

Adding the explicit cast should shut it up.

Static analysis says:
src\zmq.cpp(489): error V220: Suspicious sequence of types castings: memsize -> 32-bit integer -> memsize. The value being casted: '* count_'.
src\zmq.cpp(510): error V127: An overflow of the 32-bit 'nread' variable is possible inside a long cycle which utilizes a memsize-type loop counter.

I've silenced the warning on line 489 and ignored the other.
But also, it looks to me like there's a serious bug here: The
out-parameter "count_" is never set to zero before we start
incrementing it. So its final value will always be between
1 and 2 times its initial value. The fix seems obvious.

[LIBZMQ-414] Fix an error in the inline assembly for Thumb2.

Fix a bug reported on the mailing list.

Both memcmp and strcmp return zero on equal, nonzero on nonequal;
so all of these tests were backwards.

The original committer fixed the failure by comparing 22 bytes instead
of the correct 21, so that the assertions would trigger only if the
22nd byte happened to match exactly --- which was rare.

The correct fix is to compare the right number of bytes with the
right sense.  (I think all of the ".addr" fields are null-terminated,
in which case it's more appropriate to use strcmp throughout.)

Notice that ZeroMQ has never been compiled for Thumb2 before,
and I personally don't make any guarantees that it will actually
behave correctly once compiled. But after this patch, it is at
least *possible* to compile it for Thumb2.

(Thumb2 is the target for most iOS devices.)

Exchange greeting messages for all socket types

Fixes #415.

Revert zmq_poll NULL poll items check to 2.2 behavior - let the poll items count filter out empty poll sets and not return a sometimes unexpected EFAULT error status

Fix reordering compile errors

Fix invalid address metadata for ZMQ_EVENT_DISCONNECTED

Fix issue #406

When a peer reconnects, the router socket receives an identity
message containing this peer id. When this happens, the current
implementation crashes.

This patch makes a router socket to silently ignore all identity
messages coming from reconnected peers.

Fix LIBZMQ-404: zmq_term not truly re-entrant

zmq_term can not safely be re-entered with pgm transport.
Fix proposed by Steven McCoy.

Correction for LIBZMQ-335

That way it can be used more appropriately between processes.

By assigning a SECURITY_DESCRIPTOR to the event we gain the ability to
share it between service and console programs. We also added
EVENT_MODIFY_STATE as a requirement to OpenEvent so we can SetEvent later
in the method.

Revert zmq_poll NULL poll items check to 2.2 behavior - let the poll items count filter out empty poll sets and not return a sometimes unexpected EFAULT error status

Small code cleanup

Fix issue #397