[MS-ABI] Fixed alias-avoidance padding in the presence of vtordisps
If a vtordisp exists between two bases, then there is no need for 
additional alias avoidance padding.  Test case included.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206087 91177308-0d34-0410-b5e6-96231b3b80d8