pg_ctl: Disable autoruns for cmd.exe on Windows

On Windows, cmd.exe is used to launch the postmaster process to ease its
redirection setup.  However, cmd.exe may execute other programs at
startup due to autorun configurations, which could influence the
postmaster startup.  This patch adds /D flag to the launcher cmd.exe
command line to disable autorun settings written in the registry.

This was originally applied on HEAD as of 9886744a36 without a
backpatch, but the patch has survived CI and buildfarm cycles.  I have
checked that cmd /d exists down to Windows XP, which should make this
change work correctly in the oldest branches still supported.

Reported-by: Hayato Kuroda
Author: Kyotaro Horiguchi
Reviewed-by: Robert Haas, Michael Paquier
Discussion: https://postgr.es/m/20230922.161551.320043332510268554.horikyota.ntt@gmail.com
Backpatch-through: 12

src/bin/pg_ctl/pg_ctl.c

@@ -559,11 +559,11 @@ start_postmaster(void)
 		else
 			close(fd);
 
-		cmd = psprintf("CMD /C \"\"%s\" %s%s < \"%s\" >> \"%s\" 2>&1\"",
+		cmd = psprintf("CMD /D /C \"\"%s\" %s%s < \"%s\" >> \"%s\" 2>&1\"",
 					   exec_path, pgdata_opt, post_opts, DEVNULL, log_file);
 	}
 	else
-		cmd = psprintf("CMD /C \"\"%s\" %s%s < \"%s\" 2>&1\"",
+		cmd = psprintf("CMD /D /C \"\"%s\" %s%s < \"%s\" 2>&1\"",
 					   exec_path, pgdata_opt, post_opts, DEVNULL);
 
 	if (!CreateRestrictedProcess(cmd, &pi, false))