Remove: BeOS support (deprecated by Haiku)

In 10 years there is no commit to change how BeOS works, and we
have no active maintainer for it. It is unlikely it works in its
current state (but not impossible).

With the arrival of SDL2 (and removal of SDL), BeOS is no longer
support. SDL2 suggests to use Haiku instead of BeOS.

src/network/core/udp.cpp

@@ -94,7 +94,6 @@ void NetworkUDPSocketHandler::SendPacket(Packet *p, NetworkAddress *recv, bool a
 
 		p->PrepareToSend();
 
-#ifndef BEOS_NET_SERVER /* will work around this, some day; maybe. */
 		if (broadcast) {
 			/* Enable broadcast */
 			unsigned long val = 1;
@@ -102,7 +101,6 @@ void NetworkUDPSocketHandler::SendPacket(Packet *p, NetworkAddress *recv, bool a
 				DEBUG(net, 1, "[udp] setting broadcast failed with: %i", GET_LAST_ERROR());
 			}
 		}
-#endif
 
 		/* Send the buffer */
 		int res = sendto(s->second, (const char*)p->buffer, p->size, 0, (const struct sockaddr *)send.GetAddress(), send.GetAddressLength());