Supply timespecsub if needed.

Author: daztucker

defines.h

@@ -515,6 +515,13 @@ struct winsize {
    } while (0)
 #endif
 
+#ifndef timespeccmp
+#define	timespeccmp(tsp, usp, cmp)					\
+	(((tsp)->tv_sec == (usp)->tv_sec) ?				\
+	    ((tsp)->tv_nsec cmp (usp)->tv_nsec) :			\
+	    ((tsp)->tv_sec cmp (usp)->tv_sec))
+#endif
+
 #ifndef TIMEVAL_TO_TIMESPEC
 #define	TIMEVAL_TO_TIMESPEC(tv, ts) {					\
 	(ts)->tv_sec = (tv)->tv_sec;					\