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/ubsan.c

@@ -206,7 +206,7 @@ static void __ubsan_exit(void) {
   kprintf("your ubsan runtime needs\n"
           "\t__static_yoink(\"__die\");\n"
           "in order to show you backtraces\n");
-  _Exitr(99);
+  _Exit(99);
 }
 
 static char *__ubsan_stpcpy(char *d, const char *s) {