Make improvements

- Improve compatibility with Blink virtual machine
- Add non-POSIX APIs for joining threads and signal masks
- Never ever use anything except 32-bit integers for atomics
- Add some `#undef` statements to workaround `ctags` problems

libc/thread/pthread_setaffinity_np.c

@@ -74,6 +74,6 @@ errno_t pthread_setaffinity_np(pthread_t thread, size_t size,
     }
   }
   STRACE("pthread_setaffinity_np(%d, %'zu, %p) → %s", tid, size, bitset,
-         DescribeErrnoResult(rc));
+         DescribeErrno(rc));
   return rc;
 }