Support multiline strings in wxDC::DrawRotatedText() in wxMSW.

The native API doesn't support this, so do it by splitting the string into
lines manually.

Closes #9686.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75750 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Use automatic resource management in wxMSW wxDC::DrawRotatedText().

No real changes, just simplify the code by using RAII classes.

Also avoid unnecessary indentation by returning after checking for the special
cases.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75751 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775