Fix memory leak when using non-uniform corner radius on windows.

See: http://archive.msdn.microsoft.com/WPFShell/Thread/View.aspx?ThreadId=5355

Quoted:
I think I misread the documentation about CombineRgn and SetWindowRgn when I was writing this. SetWindowRgn takes ownership of the HRGN so I never delete them. I thought that CombineRgn kept a reference to both source HRGNs so I also didn't delete any temporary ones, but given that you're seeing this leak I believe that assumption was wrong.

I think you should be able to fix this by adding a DeleteObject call to the temporary HRGN created in WindowChromeWorker._CreateAndCombineRoundRectRgn. Alternatively, you won't hit this bug if you have a uniform corner radius on your windows.
Fix project/solution configurations so that x86 configuration works properly (very useful for edit&continue when debugging)