forked from Imagelibrary/rtems
* shared/irq/irq.c: test for non-NULL-ness before calling 'on'/'off' methods so that users don't have to provide no-ops if they don't want this feature.
* shared/irq/irq.c: test for non-NULL-ness before calling 'on'/'off' methods so that users don't have to provide no-ops if they don't want this feature.