Trade: explicitly link tests to CORRADE_PLUGINMANAGER_LIBRARIES.
Trade: explicitly link tests to CORRADE_PLUGINMANAGER_LIBRARIES.

Compilation of tests in static build fails with missing
reference to dlclose().

ashimidashajia/magnum,DerThorsten/magnum,DerThorsten/magnum,ashimidashajia/magnum,DerThorsten/magnum,DerThorsten/magnum,ashimidashajia/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum,MiUishadow/magnum,MiUishadow/magnum,ashimidashajia/magnum