Do not set the callbacks to 0 when the dynamic scopes are disabled.


git-svn-id: https://root.cern.ch/svn/root/trunk@48851 27541ba8-7e3a-0410-8455-c3a389f83636
Adapt the code for the dynamic scope's lifetime handler. Its ctor has new signature
and we need to pass in the gCling variable.

Fixes one of cling standalone test failures.


git-svn-id: https://root.cern.ch/svn/root/trunk@48852 27541ba8-7e3a-0410-8455-c3a389f83636