[analyzer] Warn when a ‘nil’ object is added to NSArray or NSMutableArray.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177318 91177308-0d34-0410-b5e6-96231b3b80d8
Centralize the recording of which tools have been constructed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177319 91177308-0d34-0410-b5e6-96231b3b80d8