Make signal handling work well across platforms

- Fix sigsuspend() on XNU
- Fix strsignal() on non-Linux
- Add unit tests for strsignal()
- Add unit tests for setitimer()
- Add unit tests for sigsuspend()
- Rewrite setitimer() for New Technology
- Rewrite nanosleep() for New Technology
- Polyfill SIGALRM on the New Technology
- select(0,0,0,0) on NT now calls pause()
- Remove some NTDLL calls that aren't needed
- Polyfill SA_NOCLDWAIT on the New Technology
- Polyfill SA_RESETHAND on the New Technology
- Polyfill sigprocmask() on the New Technology
- Polyfill SIGCHLD+SIG_IGN on the New Technology
- Polyfill SA_RESTART masking on the New Technology
- Deliver console signals from main thread on New Technology
- Document SA_RESTART behavior w/ @sarestartable / @norestart
- System call trace in MODE=dbg now prints inherited FDs and signal mask

libc/calls/clock_gettime.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/calls/internal.h"
+#include "libc/calls/strace.internal.h"
 #include "libc/calls/struct/timeval.h"
 #include "libc/dce.h"
 #include "libc/fmt/conv.h"
@@ -39,9 +40,10 @@
  * @see strftime(), gettimeofday()
  * @asyncsignalsafe
  */
-int clock_gettime(int clockid, struct timespec *ts) {
+noinstrument int clock_gettime(int clockid, struct timespec *ts) {
   int rc, e;
   axdx_t ad;
+  char buf[45];
   if (!ts) {
     rc = efault();
   } else if (IsAsan() && !__asan_is_valid(ts, sizeof(*ts))) {
@@ -64,6 +66,9 @@ int clock_gettime(int clockid, struct timespec *ts) {
   } else {
     rc = sys_clock_gettime_nt(clockid, ts);
   }
-  /* TODO(jart): Add get_clock_gettime() so we can STRACE() */
+  if (!__time_critical) {
+    STRACE("clock_gettime(%d, [%s]) → %d% m", clockid,
+           __strace_timespec(buf, sizeof(buf), rc, ts), rc);
+  }
   return rc;
 }