[analyzer] pr32088: Don't destroy the temporary if its initializer causes return.

In the following code involving GNU statement-expression extension:
  struct S {
    ~S();
  };

  void foo() {
    const S &x = ({ return; S(); });
  }
function 'foo()' returns before reference x is initialized. We shouldn't call
the destructor for the temporary object lifetime-extended by 'x' in this case,
because the object never gets constructed in the first place.

The real problem is probably in the CFG somewhere, so this is a quick-and-dirty
hotfix rather than the perfect solution.

A patch by Artem Dergachev!

rdar://problem/30759076

Differential Revision: https://reviews.llvm.org/D30499

llvm-svn: 296646