[WinCairo] Unreviewed build fix after r170937.

* WebCore.vcxproj/WebCoreGeneratedWinCairo.make:
Update and apply changes applied to WebCoreGenerated.make in r170937.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@171019 268f45cc-cd09-0410-ab3c-d52691b4dbfc