ClangTidy misc-argument-comment check: don't check arguments to template
parameter packs.

Summary:
This disables this check for std::bind and similar functions that use
parameter packs to forward arguments to a different function. Name of the
parameter pack argument doesn't matter.

Reviewers: klimek

Reviewed By: klimek

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D5168