use nullptr

Author: minxuanz

compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp

@@ -109,11 +109,11 @@ void SetTimer(int Seconds) {
     {Seconds, 0}, { Seconds, 0 }
   };
   SetSigaction(SIGALRM, AlarmHandler);
-  if (timer_create(CLOCK_REALTIME, NULL, &timerid) == -1) {
+  if (timer_create(CLOCK_REALTIME, nullptr, &timerid) == -1) {
     Printf("libFuzzer: timer_create failed with %d\n", errno);
     exit(1);
   }
-  if (timer_settime(timerid, 0, &T, NULL) == -1) {
+  if (timer_settime(timerid, 0, &T, nullptr) == -1) {
     Printf("libFuzzer: timer_settime failed with %d\n", errno);
     exit(1);
   }