Fixes an assertion failure when ivar is a struct containing incomplete
array. Also completes support for direct flexible array members.
rdar://problem/21054495
Reviewers: rjmccall, theraven
Reviewed By: rjmccall
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D38774
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@316723 91177308-0d34-0410-b5e6-96231b3b80d8