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/intrin/describepersonalityflags.c

@@ -36,8 +36,7 @@ static const struct DescribeFlags kPersonalityFlags[] = {
     {UNAME26, "UNAME26"},                        //
 };
 
-const char *DescribePersonalityFlags(int x) {
-  _Alignas(char) static char personalityflags[128];
-  return DescribeFlags(personalityflags, sizeof(personalityflags),
-                       kPersonalityFlags, ARRAYLEN(kPersonalityFlags), "", x);
+const char *(DescribePersonalityFlags)(char buf[128], int x) {
+  return DescribeFlags(buf, 128, kPersonalityFlags, ARRAYLEN(kPersonalityFlags),
+                       "", x);
 }