Per-game config: Don't save control settings unless customized

[hrydgard]

While this isn't really perfectly consistent with the rest of the saved settings, I think it would make sense to only create the [ControlMapping] section in the per-game ini files if anything has actually been changed there.

mrfixit alerted me to the fact that it can be quite annoying that control mappings are kind of "frozen" with each per-game config.

Not sure exactly how to best implement it - somewhere we need to make a special case.

[retro-center]

Thanks @hrydgard!

It might make sense to expand the scope of this to also compare other sections like [Control], [Sound], [SystemParam], and [Network]. If there's no changes - it's just duplicating data.

Looking forward to this patch!

[iota97]

I have a feeling this might be confusing somehow

If I create custom config for 2 games I might only update one when I change a 3rd one with global settings

Not sure if the reason will be obvious enough :/

May be fine with controls, would avoid for network or system settings as if something break it might be hard to understand why or where to look

PS: if we manage to get #15406 in it will be easier to copy the global setting to the custom one at least

[KingPepper57]

Just a addition to this issue / upgrade - Not to sure if this belongs here, but lets see, what you guys think.
I was thinking along the lines of being able to save a custom keys file, of which you can actually name it.
IE FPS shooter keys, or Driving games keys, etc etc etc, depending on the genre of the game, as some games for instance use the face buttons as a way of controlling a cursor for shoot em ups, have a custom setup for those type of games, would be a awesome addition.