Make fixes and improvements

- Introduce __assert_disable global
- Improve strsignal() thread safety
- Make system call tracing thread safe
- Fix SO_RCVTIMEO / SO_SNDTIMEO on Windows
- Refactor DescribeFoo() functions into one place
- Fix fork() on Windows when TLS and MAP_STACK exist
- Round upwards in setsockopt(SO_RCVTIMEO) on Windows
- Disable futexes on OpenBSD which seem extremely broken
- Implement a better kludge for monotonic time on Windows

libc/testlib/benchrunner.c

@@ -54,7 +54,6 @@ void testlib_benchwarmup(void) {
 void testlib_runallbenchmarks(void) {
   int e;
   e = errno;
-  _peekall();
   if (!IsWindows()) {
     mlockall(MCL_CURRENT);
     nice(-1);