[C++11] Suggest placing callable arguments as the last argument to
facilitate the nice formatting of lambdas passed there. Suggested by
Chris during review of my lambda additions, and something I strongly
agree with.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202622 91177308-0d34-0410-b5e6-96231b3b80d8