Retry failed shutdown in Windows smoke testing

It seems like Windows is unhappy if the app fails to close when
forcefully killed. Failure here seems to be because the PID
disappears, because killing one related pid kills some of the
others? Regardless, it doesn't really matter from our point of
view.

Author: pimterry

test/distributables-test/windows.bat

@@ -51,4 +51,4 @@ exit /b %err%
 echo All good.
 
 REM Shut down by matching title passed to START to run in the background
-taskkill /FI "WindowTitle eq server*" /T /F
+taskkill /FI "WindowTitle eq server*" /T /F || goto :success