MS ABI: Add an additional test for typeid

This tests typeid with polymorphic arguments which have an extendable
virtual function table.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211505 91177308-0d34-0410-b5e6-96231b3b80d8
Driver: correct behaviour of -fmsc-version=MAJOR

Ensure that we properly handle the case where just the major version component
is provided by the user.

Thanks to Alp Toker for pointing out that this was not handled correctly!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211506 91177308-0d34-0410-b5e6-96231b3b80d8