+/*
+ * Function: grabCapability(Capability**)
+ *
+ * Purpose: the act of grabbing a capability is easy; just
+ * remove one from the free capabilities list (which
+ * may just have one entry). In threaded builds, worker
+ * threads are prevented from doing so willy-nilly
+ * through the use of the sched_mutex lock along with
+ * condition variables thread_ready_cond and
+ * returning_worker_cond.
+ *
+ * Pre-condition: sched_mutex is held (in threaded builds only).
+ *
+ */