In C++-Interop mode some of the Foundation @availables were not getting
their "renamed:" attributes filled in and this was because of the
LookupName issue as we have seen before where LookupName bails in C++
mode due to a nullptr scope resulting in something not getting imported
completely.
This patch merely passes a TUscope to avert this.
I believe ignoring the existing enum issues this should bring
Foundation with C++-Interop to parity with ObjC-Interop.
