Template argument deduction is no longer responsible for checking

non-dependent parameter types. Instead, class template partial
specializations perform a final check of all of the instantiated
arguments. This model is cleaner, and works better for function
templates where the "final check" occurs during overload resolution.

Also, cope with cv-qualifiers when the parameter type was originally a
reference type, so that the deduced argument can be more qualified
than the transformed argument.

llvm-svn: 74323