VMManager: Avoid use-after-move conditions

[F0bes]

Description of Changes

Removes two possible move-after-frees in the vmmanager

Rationale behind Changes

Using an object (like an std::string) after it has been moved I believe is undefined behaviour, or implementation defined behaviour. Not good nonetheless.

Suggested Testing Steps

Change discs and savestate when you can't rename to backup.

[TellowKrinkle]

Using an object (like an std::string) after it has been moved I believe is undefined behaviour, or implementation defined behaviour. Not good nonetheless.

Moves leave the input in a valid but otherwise indeterminate state, so no UB.
Still not very helpful though.

[F0bes]

Using an object (like an std::string) after it has been moved I believe is undefined behaviour, or implementation defined behaviour. Not good nonetheless.

Moves leave the input in a valid but otherwise indeterminate state, so no UB. Still not very helpful though.

Thanks for the clarification.