Don't destroy wxFont from its GetFaceName() in wxMSW.

wxFont::GetFaceName() could destroy the HFONT used by the font accidentally,
avoid it by not invalidating the font when caching its face name.

Closes #16273.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76592 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775