Add a testcase for using objects with list-constructors, and fix a Sema crash...

Add a testcase for using objects with list-constructors, and fix a Sema crash by repeating an old hack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150925 91177308-0d34-0410-b5e6-96231b3b80d8