Several improvements to template argument deduction:

Several improvements to template argument deduction:
  - Once we have deduced template arguments for a class template partial
    specialization, we use exactly those template arguments for instantiating
    the definition of the class template partial specialization.
  - Added template argument deduction for non-type template parameters.
  - Added template argument deduction for dependently-sized array types.

With these changes, we can now implement, e.g., the remove_reference
type trait. Also, Daniel's Ackermann template metaprogram now compiles
properly.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72909 91177308-0d34-0410-b5e6-96231b3b80d8