[analyzer] Move the DeadStores checker out of the 'core' package.

-Now it gets enabled with '-analyzer-checker=DeadStores'.
-The driver passes the above flag by default.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126612 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed