newcodecmodel: fix priority change when compiled with clang

- clang++ std::swap works with pre-inc/dec and g++ with post so
  we use std::iter_swap and std::advance wrappers which produce
  the same results on both compilers

Change-Id: I12a2c1f3854126096d3f4ba780c4b619c5497493
Reviewed-by: Sebastien Blin <sebastien.blin@savoirfairelinux.com>