Cling workaround (#100389): prevent crash and instead raise python exception


git-svn-id: https://root.cern.ch/svn/root/trunk@48550 27541ba8-7e3a-0410-8455-c3a389f83636
Cling workaround (#100389): return raw memory on construction if no default ctor available;
this only works for PODS though, but those are where missing default ctors are the most
common anyway


git-svn-id: https://root.cern.ch/svn/root/trunk@48551 27541ba8-7e3a-0410-8455-c3a389f83636