Include optional dependencies in pom.xml at surefire level

running tests during a tycho build on MacOSX requires an optional/platform specific bundle (o.e.jdt.launching.macosx) that is currently defined in a profile.
Problem is that this profile includes all optional dependencies, not only this one, while other profiles (ie, platform) include no optional dependency at all.

Solution: configure this optional dependency at the surefire level and for macosx only