Fix the -cxx-abi microsoft -mconstructor-aliases combination.

On the microsoft ABI clang is producing one weak_odr and one linkonce_odr
destructor, which is reasonable since only one is required.

The fix is simply to move the assert past the special case treatment of
linkonce_odr.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194158 91177308-0d34-0410-b5e6-96231b3b80d8