so that *really* all non-installed tools are properly registered.
if some day we have more build scripts, this code should be centralized
in a .prf file.

Change-Id: I5b292a4b30199cb59838319f2dc9f88cd54bb57d
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>