Ignore "%*" in the shell command strings in MSW registry.

Ignore "%*" in the shell command strings in MSW registry.

Apparently "%*" can be used now in addition to the usual "%1" in the MSW shell
command strings. As we don't support passing more than one file to a command
at once anyhow, simply ignore them. At least this avoids errors when trying to
open files with some extensions.

Closes #12091.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64416 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775