Add timespec/timeval conversion helpers.

TIMESPEC_TO_TIMEVAL and TIMEVAL_TO_TIMESPEC are usually provided by
sys/time.h.

BUG: 22532790

Change-Id: I8b9d7298e3250323faa20b1adf9a7514954c6096

libc/include/sys/time.h

@@ -73,6 +73,15 @@ extern int utimes(const char *, const struct timeval *);
         }                                             \
     } while (0)
 
+#define TIMEVAL_TO_TIMESPEC(tv, ts) {     \
+    (ts)->tv_sec = (tv)->tv_sec;          \
+    (ts)->tv_nsec = (tv)->tv_usec * 1000; \
+}
+#define TIMESPEC_TO_TIMEVAL(tv, ts) {     \
+    (tv)->tv_sec = (ts)->tv_sec;          \
+    (tv)->tv_usec = (ts)->tv_nsec / 1000; \
+}
+
 __END_DECLS
 
 #endif /* _SYS_TIME_H_ */