Fix warnings with MinGW

src/ip.cpp

@@ -92,6 +92,8 @@ void zmq::unblock_socket (fd_t s_)
 
 void zmq::enable_ipv4_mapping (fd_t s_)
 {
+  (void) s_;
+
 #ifdef IPV6_V6ONLY
 #ifdef ZMQ_HAVE_WINDOWS
     DWORD flag = 0;
@@ -107,3 +109,4 @@ void zmq::enable_ipv4_mapping (fd_t s_)
 #endif
 #endif
 }
+

src/signaler.cpp

@@ -234,8 +234,10 @@ int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
     return 0;
 
 #elif defined ZMQ_HAVE_WINDOWS
-    SECURITY_DESCRIPTOR sd = {0};
-    SECURITY_ATTRIBUTES sa = {0};
+    SECURITY_DESCRIPTOR sd;
+    SECURITY_ATTRIBUTES sa;
+    memset (&sd, 0, sizeof (sd));
+    memset (&sa, 0, sizeof (sa));
 
     InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION);
     SetSecurityDescriptorDacl(&sd, TRUE, 0, FALSE);