Add new target for make

"make cleanlib" will remove all Cbm libraries and related dictionaries
from the lib folder of the build directory but do not delete the libraries
from the external packages. Using "make cleanlib" with a subsequent "make"
will trigger a regeneration of the dictionaries and a relinking of the
libraries.


git-svn-id: https://subversion.gsi.de/cbmsoft/cbmroot/trunk@15770 5a1b234a-d7ce-0410-9a93-fd649a8fa65c