[analyzer] Remove unused check::RegionChanges::wantsRegionChangeUpdate callback

Remove the check::RegionChanges::wantsRegionChangeUpdate callback as it is no
longer used (since checkPointerEscape has been added).

A patch by Krzysztof Wiśniewski!

Differential Revision: https://reviews.llvm.org/D26759

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@287175 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit c9ea9121858aa019b5faec1ba31b09479d5d6c52)
8 files changed