upgrade to wxwidgets 2.9.4 and fix built for x86_64 target

wxwidgets 2.8.12 does not built for x86_64 target, the same is true for wx2.9.4. the attached patch provides a patch for 2.9.4 and upgrades wx to 2.9.4. 

The patch has been reported upstream, too. see http://trac.wxwidgets.org/ticket/14949