include sys/types.h

I have a report that this is necessary for freebsd.
It seemed not necessary for OSX, but even there the kqueue
man page says to include this header (along with sys/time.h
which it already does).

Utility/libkqueue.c

@@ -10,6 +10,7 @@
 #include <fcntl.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <sys/types.h>
 #include <sys/event.h>
 #include <sys/time.h>
 #include <errno.h>