Actually implement default wxPasswordEntryDialog ctor.

This was added in r75404 but not implemented, do provide the trivial
definition of this function too.

Closes #15770.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75564 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775