[-Wunreachable-code] Handle 'return' with no argument dominated by 'noreturn' function.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203333 91177308-0d34-0410-b5e6-96231b3b80d8
[CFG] Record would-be successor for noreturn destructor.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203334 91177308-0d34-0410-b5e6-96231b3b80d8
Fix CFG bug where the 'isTemporaryDtorsBranch' bit was silently lost for terminators.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203335 91177308-0d34-0410-b5e6-96231b3b80d8
[-Wunreachabe-code] Don't warn about unreachable destructors for temporaries.

This can possibly be refined later, but right now the experience
is so incomprehensible for a user to understand what is going on
this isn't a useful warning.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203336 91177308-0d34-0410-b5e6-96231b3b80d8