The event synchronizer can be used to safely transfer 1-bit 1-clock cycle
event signals from one clock domain to another.
For each event recorded in the source domain it is guaranteed that a event
will be generated in the target domain at a later point in time. It is
possible though that multiple events in the source domain will be coalesced
into a single event in the target domain if events are generated faster
than they can be transferred.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>