ObjectiveC migrator: When doing migration, migrator must suggest
migration of headers which have become system headers by user having put
the .system_framework in the sdk directory.
// rdar://15066802


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191796 91177308-0d34-0410-b5e6-96231b3b80d8