Enable the user to control whether CXXConstructExpr will be added as a

block-level expr. Currently CXXConstructExpr is always added as a block-level
expr. This caused two problems for the analyzer (and potentially for the
CFG-based codegen).
1. We have no way to know whether a ctor call is base or complete.
2. We have no way to know the destination object being contructed.

llvm-svn: 147306