Make improvements for Actually Portable Emacs

- Get SIGWINCH working again on the New Technology
- Correctly handle O_NOFOLLOW in open() on Windows
- Implement synthetic umask() functionality on Windows
- Do a better job managing file execute access on Windows
- Fill in `st_uid` and `st_gid` with username hash on Windows
- Munge UNICODE control pictures into control codes on Windows
- Do a better job ensuring Windows console settings are restored
- Introduce KPRINTF_LOG environment variable to log kprintf to a file

libc/intrin/quick_exit.c

@@ -31,7 +31,6 @@
 wontreturn void quick_exit(int exitcode) {
   const uintptr_t *p;
   STRACE("quick_exit(%d)", exitcode);
-  _restorewintty();
   if (_weaken(fflush)) {
     _weaken(fflush)(0);
   }