Update argument parsing in hadd to support the often typed:

   hadd -f output.root -T input1.root input2.root

to properly recognize the 'output.root' to be the output rather than input1.root
(i.e. previously the first argument after all the -* option was assumed to be
the output even if it was specified before hand).


git-svn-id: http://root.cern.ch/svn/root/trunk@41436 27541ba8-7e3a-0410-8455-c3a389f83636