patch D3PDPerfStats to work with recent root (>=5.34,18)

Adapt to the changes made upstream in the root code, without
re-generating the D3PDReader. For more details, see
http://root.cern.ch/gitweb?p=root.git;a=commitdiff;h=d2e8257428c1b30dd0ca254c3cc1230e14a8eee6
re-build root packaged for travis test (5.18->5.22)
Merge pull request #36 from gerbaudo/susytools-05-14

patch D3PDPerfStats to work with recent root (>=5.34,18)