the unmapped page.
* This is needed by everyone who calls this to make sure modifications to a
page aren't ignored. Namely, the page scanner and the page thief were
affected.
* Cleaned up locking the page's cache a bit in page_thief(); there is now
a helper class that takes care of everything.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22438 a95241bf-73f2-0310-859d-f6bbb57e9c96