swift234

Two changes:
 - In name lookup, if we find a decl that is already being type checked 
   (which only occurs on illegal code) just assume it is acceptable instead
   of blowing up with an assertion checking access control that hasn't been
   evaluated yet.
 - In checkInheritanceClause, make sure that the we mark the decl being
   resolved as being type checked when resolving the types involved.  That way,
   cyclic references are detected as invalid, instead of causing assertions and
   other explosions.

This fixes some compiler crashers.



Swift SVN r29538