SDL2.0 introduces a new input backend for XInput devices. These have a
different layout (buttons, axis, hats, ...) than the previous backends. This
makes the current AutoConfig entries for such devices useless. Unfortunatelly,
SDL2 doesn't inform us about the backend used to talk to a joystick/gamepad.
This makes it hard to decide whether we must search for an entry without
prefix, with Win32 prefix or with a new "XInput" prefix.
Instead the whole ini is parsed and it is not stopped when a section with a
valid entry is finished. Priorities are saved to decide whether a new found
section is interesting for the user config or not. Entries without a known
prefix have the priority 3, one with a known entry have the priority 2 and
entries with the prefix "XInput" get the priority of 1 on windows with SDL2.
The lowest priority is always preferred.
This allows the autoconfiguration to use XInput configs whenever it is
required and use the old configurations everywhere else.