[Libreoffice] Make .component files directly usable within UNO_SERVICES

<http://cgit.freedesktop.org/libreoffice/core/commit/?id=f66ac2934303e789014741547a06c98ab5433ca0> 
makes tests a little simpler (but also requires another round of "find 
*/${INPATH?}/ -name \*.component -exec rm {} \;" for non-clean builds):

* solenv/bin/createcomponent.xslt now simply surrounds it output by 
<components>, so all the generated component files can be directly 
consumed as service "rdbs" (as listed in the UNO_SERVICES bootstrap 
variable) by the UNO runtime.

* solenv/gbuild/CppunitTest.mk got new functions 
gb_CppunitTest_add[_old]_component[s] (like their gb_RdbTarget_ 
predecessors), to directly list such component files in CppUnit tests.

* 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 solenv/gbuild/ComponentsTarget.mk (which 
I invented recently to generate via packcomponents.xslt the 
multi-component files used by oxt extensions, unaware that RdbTarget.mk 
would already do the same thing; also, it turned out I did not need to 
create such oxt extensions at that time at all, so ComponentsTarget.mk 
is currently unused.)

Stephan