GUI: AUTOSAVE OPTION: Enabling Autosave displays warning when no non-autosave saved games exist.

[macca8]

If the autosave slot for each installed game is either empty or contains a valid autosave saved game, then surely this warning shouldn't be displayed to the user when enabling the feature.

A picture speaks a thousand words (see attached).

Refers to commit ​873ba58 - Warn when enabling autosave on options if non-autosave games are stored in autosave slot.
The commit message and code clearly target listing only non-autosave games, however, it seems that no consideration has been made for that list to be empty, thus prompting an unnecessary warning.

If I'm understanding this commit correctly, it also attempts to minimize the number of game engines that need to be tested, by constructing a sample size of 10 non-autosave games, rather than a complete list (but I may be mistaken). It follows that, if this list is empty (or less than 10), then testing will continue until all game engines have been tested, which may not be the desired outcome for those with a large number of games installed.