git-gui (Windows): use git-gui.exe in `Create Desktop Shortcut`
When calling `Repository>Create Desktop Shortcut`, Git GUI assumes
that it is okay to call `wish.exe` directly on Windows. However, in
Git for Windows 2.x' context, that leaves several crucial environment
variables uninitialized, resulting in a shortcut that does not work.
To fix those environment variable woes, Git for Windows comes with a
convenient `git-gui.exe`, so let's just use it when it is available.
This fixes https://github.com/git-for-windows/git/issues/448
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>