When checking access control for an instance member access on

When checking access control for an instance member access on
an object of type I, if the current access target is protected
when named in a class N, consider the friends of the classes P
where I <= P <= N and where a notional member of N would be
non-forbidden in P.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112358 91177308-0d34-0410-b5e6-96231b3b80d8