scheduling a Datawarp job.

The assoc_mgr lock needs to happen before the bb_state.bb_mutex.  One place
this could cause deadlock is from src/slurmctld/controller.c
_accounting_cluster_ready() which calls clusteracct_storage_g_cluster_tres
which inturn calls bb_g_job_set_tres_cnt which calls bb_p_job_set_tres_cnt
which will lock the bb_muxtex after the assoc_mgr is already locked.

Bug 3389