* solenv/bin/createcomponent.xslt simply surrounds it output by <components>.
* solenv/gbuild/CppunitTest.mk got new functions
gb_CppunitTest_add[_old]_component[s] (like their gb_RdbTarget_ predecessors).
* This obsoleted current uses of solenv/gbuild/RdbTarget.mk, which also does not
work currently, as it catenates the input component files instead of passing
them through packcomponents.xslt (which now takes care about the surrounding
<components> in the input).  In the future, it will likely be combined with the
recently added solenv/gbuild/ComponentsTarget.mk.