Replace the setsets in the MC's states by malloced arrays.

Replace the setsets in the MC's states by malloced arrays.
In the case that a process has multiple transitions enabled
(like when executing a waitany request) the process should be
several times in the interleave set, so we need multisets, and
the setsets are useless.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/simgrid/simgrid/trunk@9355 48e7efb5-ca39-0410-a469-dd3cf9ba447f