Correction to crash inside RtlCaptureStackBackTrace() + test case

[Dan Kegel]

Hi Janne,
I haven't reviewed your code, but I can suggest sending each
patch as a separate message to wine-patches, and using titles more like
  ntdll: test corrupt stack frame in RtlCaptureStackBackTrace()
  ntdll: handle corrupt stack frame in RtlCaptureStackBackTrace()
and mention clearly that this fixes the online store in Anarchy Online
(if it does).

Also, please send the test patch by itself through winebot before posting
and verify that it passes on all flavors of windows.

See http://wiki.winehq.org/SubmittingPatches

Thanks!