Use SAL_WARN, too, to increase chance of actually seeing the message

Passing an, as such useful, verbose error message to the
CannotActivateFactoryException constructor is fairly pointless if that
exception ends up being unexpected and causes program
termination. Which of course is exactly the case when one would be
very interested in seeing any message associated with the exception.

Change-Id: I1cd987669e39e47d5f072690dc5013e4a42fd50a