At the moment, we can only use crank if the pending entry is in the
future. This patch leaves the clock time to the same point if the
pending entry was in the past. This still execute a single entry. This
will be needed for the jitterbuffer, since as soon as we stop waking up
the jitterbuffer when the timer is reschedule later, we may endup with
such case in the unit tests.
Related to #608
Keep it simple. Likely also makes things easier for bindings,
and efficiency clearly has not been a consideration given how
the existing code handled these lists.
In order to be deterministic, multiple waiting GstClockIDs needs to be
released at the same time, or else one can get into the situation that
the one being released first can add itself back again before the next
one waiting is released.
Test added for new API and old tests rewritten to comply.
