make-file-list: include the new /etc/msystem.d/ folder

As of filesystem-2025.05.08-1, the various definitions depending on the
environment variable `MSYSTEM` are no longer in a single `/etc/msystem`
file, but rather in files in the new `/etc/msystem.d/` directory whose
filenames reflect the value of said environment variable.

As per the suggestion in
git-for-windows/git-sdk-64#99 (comment),
let's include this directory in the payload of Git for Windows'
installer so that users are not greeted with the message:

	bash: /etc/msystem.d/MSYS: No such file or directory

Suggested-by: Jeremy Drake <github@jdrake.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

make-file-list.sh

@@ -401,7 +401,7 @@ then
 	etc/profile
 	etc/profile.d/lang.sh
 	etc/bash.bashrc
-	etc/msystem
+	etc/msystem*
 	usr/bin/dash.exe
 	usr/bin/getopt.exe
 	EOF