Fix a couple of cases where we would fail to correctly parse deduced class template...

Fix a couple of cases where we would fail to correctly parse deduced class template specialization types.

Specifically, we would not properly parse these types within template arguments
(for non-type template parameters), and in tentative parses. Fixing both of
these essentially requires that we parse deduced template specialization types
as types in all contexts, even in template argument lists -- in particular,
tentative parsing may look ahead and annotate a deduced template specialization
type before we figure out that we're actually supposed to treat the tokens as a
template-name. We deal with this by simply permitting deduced template
specialization types when parsing template arguments, and converting them to
template template arguments.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@326299 91177308-0d34-0410-b5e6-96231b3b80d8