Re-applying r214962.

Changes to the original patch:
- model the CFG for temporary destructors in conditional operators so that
  the destructors of the true and false branch are always exclusive. This
  is necessary because we must not have impossible paths for the path
  based analysis to work.
- add multiple regression tests with ternary operators

Original description:
Fix modelling of non-lifetime-extended temporary destructors in the
analyzer.

Changes to the CFG:
When creating the CFG for temporary destructors, we create a structure
that mirrors the branch structure of the conditionally executed
temporary constructors in a full expression.
The branches we create use a CXXBindTemporaryExpr as terminator which
corresponds to the temporary constructor which must have been executed
to enter the destruction branch.

2. Changes to the Analyzer:
When we visit a CXXBindTemporaryExpr we mark the CXXBindTemporaryExpr as
executed in the state; when we reach a branch that contains the
corresponding CXXBindTemporaryExpr as terminator, we branch out
depending on whether the corresponding CXXBindTemporaryExpr was marked
as executed.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@215096 91177308-0d34-0410-b5e6-96231b3b80d8