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/quota.c

@@ -52,7 +52,7 @@ static relegated void DieBecauseOfQuota(int rc, const char *message) {
   gethostname(hostname, sizeof(hostname));
   kprintf("%s on %s pid %d\n", message, hostname, (long)getpid());
   PrintBacktraceUsingSymbols(2, 0, GetSymbolTable());
-  _Exitr(rc);
+  _Exit(rc);
 }
 
 static relegated void OnXcpu(int sig) {
@@ -88,7 +88,7 @@ relegated void __oom_hook(size_t request) {
   kprintf("\nTHE STRAW THAT BROKE THE CAMEL'S BACK\n");
   PrintBacktraceUsingSymbols(2, 0, GetSymbolTable());
   PrintSystemMappings(2);
-  _Exitr(42);
+  _Exit(42);
 }
 
 static textstartup void InstallQuotaHandlers(void) {