Recover from missing 'typename' in sizeof(T::InnerType)

Summary:
'sizeof' is a UnaryExprOrTypeTrait, and it can contain either a type or
an expression.  This change threads a RecoveryTSI parameter through the
layers between TransformUnaryExprOrTypeTrait the point at which we look
up the type.  If lookup finds a single type result after instantiation,
we now build TypeSourceInfo for it just like a normal transformation
would.

This fixes the last error in the hello world ATL app that I've been
working with, and it now links and runs with clang.  Please try it and
file bugs!

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D4108