Fix an issue where certain CommandObjects (or Options thereof) were being...

Fix an issue where certain CommandObjects (or Options thereof) were being created once, bound to a specific CommandInterpreter (and hence a specific Debugger), and then cached for reuse across different Debugger instances

Obviously, if the original Debugger goes away, those commands are holding on to now stale memory, which has the potential to cause crashes

Fixes rdar://24460882

llvm-svn: 259964