Improve recovery (error + fix-it) when parsing type dependent template name...

Improve recovery (error + fix-it) when parsing type dependent template name without the "template" keyword.

For example:
   typename C1<T>:: /*template*/ Iterator<0> pos; 

Also the error is downgraded to an ExtWarn in Microsoft mode.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128387 91177308-0d34-0410-b5e6-96231b3b80d8