Don't output diplicate classes to rlibmap-generated rootmap
Don't output diplicate classes to rlibmap-generated rootmap

Duplicates could show in at least two ways:

(1) duplicate lines in LinkDef file
(2) same LinkDef file given a number of times

This minimal patch should solve both cases even if the same file is added
multiple times under different paths.

Signed-off-by: Benjamin Bannier <fc092fe08a12cbc6b2082d9760c5fc8c03a223fd@bnl.gov>
Signed-off-by: Fons Rademakers <1ec492889ec4314e6ce1fb58ec289eb0358186c9@cern.ch>

Dr15Jones/root,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,kirbyherm/root-r-tools,tc3t/qoot,tc3t/qoot,Dr15Jones/root,kirbyherm/root-r-tools,Dr15Jones/root,kirbyherm/root-r-tools,Dr15Jones/root,Dr15Jones/root,tc3t/qoot,Dr15Jones/root,kirbyherm/root-r-tools,kirbyherm/root-r-tools,tc3t/qoot,kirbyherm/root-r-tools,tc3t/qoot,tc3t/qoot,kirbyherm/root-r-tools,Dr15Jones/root