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/execve-nt.greg.c

@@ -45,6 +45,8 @@
 #include "libc/sysv/consts/ok.h"
 #include "libc/sysv/errfuns.h"
 
+extern long __klog_handle;
+
 __msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
 __msabi extern typeof(WaitForSingleObject) *const __imp_WaitForSingleObject;
 __msabi extern typeof(GetExitCodeProcess) *const __imp_GetExitCodeProcess;
@@ -115,6 +117,12 @@ textwindows int sys_execve_nt(const char *program, char *const argv[],
   startinfo.hStdOutput = g_fds.p[1].handle;
   startinfo.hStdError = g_fds.p[2].handle;
 
+  if (_weaken(__klog_handle) &&        //
+      *_weaken(__klog_handle) != 0 &&  //
+      *_weaken(__klog_handle) != -1) {
+    __imp_CloseHandle(*_weaken(__klog_handle));
+  }
+
   // spawn the process
   rc = ntspawn(program, argv, envp, v, 0, 0, true, 0, 0, &startinfo, &procinfo);
   if (rc == -1) {