AtomicPtrCache data must be transient

This pull request is a fix for the failure in the pat1 "other" test. Data that should have been declared transient was not. This problem can be seen in IB CMSSW_7_1_ROOT6_X_2014-05-19-1400 and prior IB's. In later IB's this error is hidden by other problems.
Please merge this as soon as convenient, unless there are problems.
This change was already merged into the 7_1_X ROOT6 branch, but has not propagated to the 7_2_X ROOT6 branch, so I need to pull request it manually.
Future ROOT6 pull requests will be to 7_2_X only.
Please merge promptly.