new interface for definition sychronisation between components

Add a new optional collective operation the synchronisation of definitions between components (in addition to the mandatory def_comp and optional sync_def):

void yac_csync_def_comps (
  int num_comps, char const * comp_names );
void yac_csync_def_instance_comps (
  int yac_instance_id, int num_comps, char const * comp_names );

• collective for all processes that locally defined at least one component from the list
• all processes have to provide the same list of components
• at least one component has to be defined locally