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/testlib/testmain.c

@@ -120,6 +120,8 @@ static void FixIrregularFds(void) {
       }
     }
   }
+  // TODO(jart): delete this stuff
+  if (1) return;
   e = errno;
   if (!closefrom(3)) return;
   errno = e;