[ms-abi] Refactoring Non-virtual base layout in record layout

This refactor addresses bugzilla bug 18167 and simplifies the code at 
the same time.  Also I add a test case for the bug.  Also I make a 
non-functional change to the basic layout lit tests to make them more 
reliable (using CHECK-NEXT instead of CHECK).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197183 91177308-0d34-0410-b5e6-96231b3b80d8