check for "make test"); in some occasions if devel/libconfig is installed at
build time it can cause the wrong libconfig to be picked up, resulting in
build failures. Add a pseudo-flavour to enable them if needed.
(I didn't run into this myself but, as found by ajacoutot@, in some builds
CMake decides to list -L/usr/local/lib before -L${WRKBUILD}/Bin/Release).
a08b89d7f9