Fix Direct2D code compilation in non-Unicode build.

DirectWrite GDI interop only works with Unicode LOGFONTW, so use it explicitly
instead of LOGFONT which is LOGFONTA in non-Unicode build.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77680 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775