Delay lookup of simple default template arguments under -fms-compatibility

MSVC delays parsing of default arguments until instantiation.  If the
default argument is never used, it is never parsed.  We don't model
this.

Instead, if lookup of a type name fails in a template argument context,
we form a DependentNameType, which will be looked up at instantiation
time.

This fixes errors about 'CControlWinTraits' in atlwin.h.

Reviewers: rsmith

Differential Revision: http://reviews.llvm.org/D3995

llvm-svn: 210382