Do not include compatfd for WIN32

sigset_t, used by that header, is not available in mingw32 environments.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

cpus.c

@@ -34,7 +34,10 @@
 
 #include "qemu-thread.h"
 #include "cpus.h"
+
+#ifndef _WIN32
 #include "compatfd.h"
+#endif
 
 #ifdef SIGRTMIN
 #define SIG_IPI (SIGRTMIN+4)