Remove another default I missed before.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197437 91177308-0d34-0410-b5e6-96231b3b80d8
The preferred alignment defaults to the ABI one. Omit it if it is the same.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197440 91177308-0d34-0410-b5e6-96231b3b80d8