Add -mconstructor aliases to some tests.

clang-cl adds these, so this makes the tests a bit more realistic. These are the
tests where it would make a difference if the windows specific handling were
removed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194336 91177308-0d34-0410-b5e6-96231b3b80d8