place a ZMQ_UNUSED macro and replace all unused variables with ZMQ_UNUSED macro

Backported from zeromq/libzmq@bff2284

# Conflicts:
#	src/client.cpp
#	src/server.cpp

include/zmq.h

@@ -407,6 +407,12 @@ ZMQ_EXPORT uint8_t *zmq_z85_decode (uint8_t *dest, char *string);
 /*  Deprecated method */
 ZMQ_EXPORT int zmq_device (int type, void *frontend, void *backend);
 
+/******************************************************************************/
+/*  0MQ General                                                               */
+/******************************************************************************/
+
+#define ZMQ_UNUSED(object) (void)object
+
 #undef ZMQ_EXPORT
 
 #ifdef __cplusplus

src/dealer.cpp

@@ -34,8 +34,7 @@ zmq::dealer_t::~dealer_t ()
 
 void zmq::dealer_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void) subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_);
 

src/pair.cpp

@@ -36,8 +36,7 @@ zmq::pair_t::~pair_t ()
 
 void zmq::pair_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void)subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_ != NULL);
 

src/pull.cpp

@@ -34,8 +34,7 @@ zmq::pull_t::~pull_t ()
 
 void zmq::pull_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void)subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_);
     fq.attach (pipe_);

src/push.cpp

@@ -34,8 +34,8 @@ zmq::push_t::~push_t ()
 
 void zmq::push_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void)subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
+
     //  Don't delay pipe termination as there is no one
     //  to receive the delimiter.
     pipe_->set_nodelay ();

src/router.cpp

@@ -55,8 +55,7 @@ zmq::router_t::~router_t ()
 
 void zmq::router_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void)subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_);
 

src/stream.cpp

@@ -48,8 +48,7 @@ zmq::stream_t::~stream_t ()
 
 void zmq::stream_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void)subscribe_to_all_;
+	ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_);
 

src/tcp.cpp

@@ -84,13 +84,13 @@ void zmq::set_tcp_receive_buffer (fd_t sockfd_, int bufsize_)
 void zmq::tune_tcp_keepalives (fd_t s_, int keepalive_, int keepalive_cnt_, int keepalive_idle_, int keepalive_intvl_)
 {
     // These options are used only under certain #ifdefs below.
-    (void)keepalive_;
-    (void)keepalive_cnt_;
-    (void)keepalive_idle_;
-    (void)keepalive_intvl_;
+    ZMQ_UNUSED(keepalive_);
+    ZMQ_UNUSED(keepalive_cnt_);
+    ZMQ_UNUSED(keepalive_idle_);
+    ZMQ_UNUSED(keepalive_intvl_);
 
     // If none of the #ifdefs apply, then s_ is unused.
-    (void)s_;
+	ZMQ_UNUSED(s_);
 
     //  Tuning TCP keep-alives if platform allows it
     //  All values = -1 means skip and leave it for OS

src/tcp_address.cpp

@@ -53,7 +53,7 @@
 int zmq::tcp_address_t::resolve_nic_name (const char *nic_, bool ipv6_)
 {
     //  TODO: Unused parameter, IPv6 support not implemented for Solaris.
-    (void) ipv6_;
+	ZMQ_UNUSED(ipv6_);
 
     //  Create a socket.
     int fd = open_socket (AF_INET, SOCK_DGRAM, 0);
@@ -117,7 +117,7 @@ int zmq::tcp_address_t::resolve_nic_name (const char *nic_, bool ipv6_)
 int zmq::tcp_address_t::resolve_nic_name (const char *nic_, bool ipv6_)
 {
     //  TODO: Unused parameter, IPv6 support not implemented for AIX or HP/UX.
-    (void) ipv6_;
+    ZMQ_UNUSED(ipv6_);
 
     //  Create a socket.
     int sd = open_socket (AF_INET, SOCK_DGRAM, 0);
@@ -195,9 +195,8 @@ int zmq::tcp_address_t::resolve_nic_name (const char *nic_, bool ipv6_)
 //  This is true especially of Windows.
 int zmq::tcp_address_t::resolve_nic_name (const char *nic_, bool ipv6_)
 {
-    //  All unused parameters.
-    (void) nic_;
-    (void) ipv6_;
+	ZMQ_UNUSED(nic_);
+	ZMQ_UNUSED(ipv6_);
 
     errno = ENODEV;
     return -1;

src/xsub.cpp

@@ -45,8 +45,7 @@ zmq::xsub_t::~xsub_t ()
 
 void zmq::xsub_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 {
-    // subscribe_to_all_ is unused
-    (void) subscribe_to_all_;
+    ZMQ_UNUSED(subscribe_to_all_);
 
     zmq_assert (pipe_);
     fq.attach (pipe_);