[trace] bugfix, correct matching of link keys on trace

details:
- push new keys to the tail, get on the head
- all conclusions taken by visualizing mpi communications
of smpi traces should be reconsidered, sorry for this

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/simgrid/simgrid/trunk@9756 48e7efb5-ca39-0410-a469-dd3cf9ba447f