When pretty-printing a declaration of a pack, put the ellipsis before the name

When pretty-printing a declaration of a pack, put the ellipsis before the name
being declared, not at the end. When pretty-printing a non-type template
parameter, put the name of the parameter in the middle of the type, not at the
end.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@213718 91177308-0d34-0410-b5e6-96231b3b80d8