Add missing return statement


git-svn-id: https://root.cern.ch/svn/root/trunk@48520 27541ba8-7e3a-0410-8455-c3a389f83636
before "make install" inst/lib/clang was never deleted as we were cd'ed into
obj/.


git-svn-id: https://root.cern.ch/svn/root/trunk@48521 27541ba8-7e3a-0410-8455-c3a389f83636