Make pointcut pick up subclasses of ScalaJavaBuilder.

This fixes a problem at a customer (cleaning output folders, leading to
empty output folders after successful builds), but I could not reproduce
locally. Confirmed it works for said customer, so rolling back to main
project.

Fixed #1001995

(cherry picked from commit bcd85b3a3af3b00b3cb195b2561c1c880feac0b9)