replay: Simplify setting replay blockers

replay: Simplify setting replay blockers

replay_add_blocker() takes an Error *.  All callers pass one created
like this:

    error_setg(&blocker, QERR_REPLAY_NOT_SUPPORTED, "some feature");

Folding this into replay_add_blocker() simplifies the callers, losing
a bit of generality we haven't needed in more than six years.

Since there are no other uses of macro QERR_REPLAY_NOT_SUPPORTED,
replace the remaining one by its expansion, and drop the macro.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230207075115.1525-10-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>