Abstract the behavior of when to use base-class tail padding.

For fun, I added a comedy "actually obey the C++11 POD rules" option
which nobody is allowed to use.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173744 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed