Update to consumed analysis.

Patch by chris.wailes@gmail.com.  The following functionality was added:

* The same functionality is now supported for both CXXOperatorCallExprs and CXXMemberCallExprs.
* Factored out some code in StmtVisitor.
* Removed variables from the state map when their destructors are encountered.
* Started adding documentation for the consumed analysis attributes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189059 91177308-0d34-0410-b5e6-96231b3b80d8