libfsobasics: ReactorChannel: add new constructor
libfsobasics: ReactorChannel: add new constructor

The new constructor is needed to preserve ABI compability.

Signed-off-by: Sebastian Reichel <1ea78bda3cb6d36efdb8fc89aad6555e21b4887e@ring0.de>

slyon/debian-libfsoframework,slyon/debian-libfsoframework,slyon/debian-fso-usaged,slyon/debian-fso-deviced,slyon/debian-fso-usaged,slyon/debian-fso-deviced