Improve quality of our ANSI C clock() function

It now works most excellently across all supported operating
sytsems (earlier it didn't work on NT and XNU). Demo code is
available in examples/clock.c and this change also adds some
of the newer ANSI C time functions like timespec_get(), plus
timespec_getres() which hasn't even come out yet as it's C23

libc/calls/clock_gettime.c

@@ -66,8 +66,8 @@ int clock_gettime(int clock, struct timespec *ts) {
   }
 #if SYSDEBUG
   if (!__time_critical) {
-    STRACE("clock_gettime(%d, [%s]) → %d% m", clock, DescribeTimespec(rc, ts),
-           rc);
+    STRACE("clock_gettime(%s, [%s]) → %d% m", DescribeClockName(clock),
+           DescribeTimespec(rc, ts), rc);
   }
 #endif
   return rc;