Explicitly declare BSD's MSG_NOSIGNAL to suppress SIGPIPE

Tested on MacOS High Sierra. Recent BSD manpages for send(2) define MSG_NOSIGNAL to be 0x20000. The MacOS BSD variant doesn't declare MSG_NOSIGNAL, but does honor the value. So, we backport it.

See https://www.freebsd.org/cgi/man.cgi?query=send&sektion=2&manpath=FreeBSD+12.1-stable
Thanks deepfryed/beanstalk-client#32 (comment) for the hint

src/uFrontNMEABridge/Socket.cpp

@@ -26,12 +26,8 @@ bool Socket::create() {
     return false;
   }
 
-  int on = 1;
-  #if defined(SO_NOSIGPIPE)
-  setsockopt(m_sock, SOL_SOCKET, SO_NOSIGPIPE, (const char *) &on, sizeof(on));
-  #endif
-
   // TIME_WAIT - argh
+  int on = 1;
   return setsockopt(m_sock, SOL_SOCKET, SO_REUSEADDR, (const char *) &on, sizeof(on)) != -1;
 }
 

src/uFrontNMEABridge/Socket.h

@@ -6,9 +6,9 @@
 #ifndef Socket_HEADER
 #define Socket_HEADER
 
-// MacOS doesn't have MSG_NOSIGNAL, default to 0 / nothing
+// MacOS doesn't have MSG_NOSIGNAL, explicitly declare it
 #if defined(__APPLE__) && !defined(MSG_NOSIGNAL)
-#define MSG_NOSIGNAL 0
+#define MSG_NOSIGNAL 0x2000
 #endif