AthContainers: A few small improvements related to getConstStore().
Add an out-of-line version of getConstStore(). If it's inlined, sometimes it can't be called from the debugger. Avoid some repeated calls to getConstStore().
Add an out-of-line version of getConstStore(). If it's inlined, sometimes it can't be called from the debugger. Avoid some repeated calls to getConstStore().