Allow the parser to recover gracefully if a typename is used to introduce a decltype type.
In Microsoft mode, we emit a warning instead of an error.

This fixes a couple of errors when parsing the MSVC 11 RC headers with clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160613 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed