Make more threading improvements

- ASAN memory morgue is now lockless
- Make C11 atomics header more portable
- Rewrote pthread keys support to be lockless
- Simplify Python's unicode table unpacking code
- Make crash report write(2) closer to being atomic
- Make it possible to strace/ftrace a single thread
- ASAN now checks nul-terminated strings fast and properly
- Windows fork() now restores TLS memory of calling thread

libc/intrin/describeiovec.c

@@ -62,7 +62,7 @@ const char *(DescribeIovec)(char buf[N], ssize_t rc, const struct iovec *iov,
            iov[i].iov_len);
   }
 
-  append("%s}", iovlen > 2 ? ", ..." : "");
+  append("}");
 
   return buf;
 }