BGQ - added head ppcfloor as an include dir when building.
Fix job preemption problem with mutliple preemption types

If a job preemption involves multiple preemption types (cancel +
requeue + suspend) and more than one job is preempted with one
of the preemption types being suspend and the other something else,
the preemptee initiation may be delayed longer than needed.
bug 377
Merge branch 'slurm-2.6'