CommonTools/TrackerMap: add missing std:: in print_TrackerMap.cc

The following is required for ROOT6.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #1961 from davidlt/add-missing-std-CommonTools-TrackerMap

Misc fixes -- CommonTools/TrackerMap: add missing std:: in print_TrackerMap.cc