AST: Propagate 'AlignIsRequired' though many levels of typedefs

A typedef of a typedef should have AlignIsRequired if *either* typedef
has an AlignAttr attached to it.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@214698 91177308-0d34-0410-b5e6-96231b3b80d8