Philippe Gerum authored Jan 30, 2021 and Jan Kiszka committed Mar 08, 2021

Dovetail allows the client core to share the common kernel clocks,
including CLOCK_REALTIME. This means the core does not have to
maintain the latter clock, but should hand over all requests to read
the clock and change its epoch to the corresponding in-band kernel
services instead. Conversely, Cobalt should keep on maintaining
CLOCK_REALTIME when running on top of the legacy I-pipe.

Abstract the management of CLOCK_REALTIME to enable such split based
on the underlying IRQ pipeline layer.

Signed-off-by: Philippe Gerum <rpm@xenomai.org>