Fixes in networking modules for 64-bit Cygwin.

- slirp: Increment IP packet ID outside of htons() to avoid undefined behaviour.
- socket: Workaround for a bug in the w32api code that generates a constant
  with wrong value. Setting up our own FIONBIO fixes the panic.
- TODO: The slirp module still fails when Bochs is compiled in Cygwin64.

bochs/iodev/network/eth_socket.cc

@@ -82,6 +82,10 @@ extern "C" {
 #ifdef WIN32
 #include <winsock2.h>
 #include <ws2tcpip.h>
+#ifdef __CYGWIN__
+#undef FIONBIO
+#define FIONBIO 0x8004667e
+#endif
 #else
 #include <errno.h>
 #include <fcntl.h>

bochs/iodev/network/slirp/ip_output.cc

@@ -74,7 +74,8 @@ ip_output(struct socket *so, struct mbuf *m0)
 	 */
 	ip->ip_v = IPVERSION;
 	ip->ip_off &= IP_DF;
-	ip->ip_id = htons(slirp->ip_id++);
+	slirp->ip_id++;
+	ip->ip_id = htons(slirp->ip_id);
 	ip->ip_hl = hlen >> 2;
 
 	/*