replay: allow runstate shutdown->running when replaying trace

replay: allow runstate shutdown->running when replaying trace

When replaying a trace, it is possible to go from shutdown to running
with a reverse-debugging step. This can be useful if the problem being
debugged triggers a reset or shutdown.

This can be tested by making a recording of a machine that shuts down,
then using -action shutdown=pause when replaying it. Continuing to the
end of the trace then reverse-stepping in gdb crashes due to invalid
runstate transition.

Just permitting the transition seems to be all that's necessary for
reverse-debugging to work well in such a state.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20240813050638.446172-5-npiggin@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240813202329.1237572-13-alex.bennee@linaro.org>