Include select.h when WIN32 is not defined

src/compat.h

@@ -34,6 +34,7 @@
 #else
 #include <sys/fcntl.h>
 #include <sys/mman.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <net/if.h>