Note: Since not all autotests are able to run from an installed location,
we need to be able to start them from the build directory, which
in turn forces us to set a destination directory for libraries and plugins,
so they will be found at run-time.

Change-Id: Idcf7e1333dfa6e9dbf745391b78c035f842ccc5a
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>