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/calls/dup3.c

@@ -21,7 +21,9 @@
 #include "libc/calls/syscall-nt.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/strace.internal.h"
+#include "libc/intrin/weaken.h"
 #include "libc/sysv/consts/o.h"
 #include "libc/sysv/errfuns.h"
 
@@ -59,6 +61,8 @@
  */
 int dup3(int oldfd, int newfd, int flags) {
   int rc;
+  // helps guarantee stderr log gets duplicated before user closes
+  if (_weaken(kloghandle)) _weaken(kloghandle)();
   if (oldfd == newfd || (flags & ~O_CLOEXEC)) {
     rc = einval();  // NetBSD doesn't do this
   } else if (oldfd < 0 || newfd < 0) {