Prevent gang scheduling with preemption configured

Prevent triggering gang scheduling within a partition if configured with
    PreemptType=partition_prio and PreemptMode=suspend,gang.
The essence of this fix is to change a "<=" to "<" in cons_res/job_test.c:
-               if ((p_ptr->part_ptr->priority <= jp_ptr->part_ptr->priority) &&
+               if ((p_ptr->part_ptr->priority < jp_ptr->part_ptr->priority) &&
but logic was also added to insure that a partition configuration with
PreemptMode did not override PreemptType != partition_prio.
bug 2232