Go back to using sprintf instead of swprintf, since it's signature has changed

Go back to using sprintf instead of swprintf, since it's signature has changed
on Windows. There are quite a few compilers where we don't know which version
the change occurred or will occur, including bcc, gcc, and icc.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43180 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775