transientVector_ must be declared transient

This is a fix for two bugs in DataFormats/TauReco/src/classes_def_3.xml, either of which is fatal in our ROOT6 branch.  ROOT 5 still works because it has looser checking for these things,
1)  One class has a dictionary defined in two different xml files.  This fix comments out the duplicate in this file.
(this fix is already in ROOT 6)
2) the data member "transientVector_" of the AssociationVector template is transient, but this dictionary fails to declare it as transient for some AssociationVector template instances.
This fix will fix a failure in 22 ROOT 6 relvals.

This pull request has been tested in the 7_1_X branch (ROOT 5) with the short relval matrix, and all tests pass with no errors.