If an optional "gamecontrollerdb.txt" file exists in the user directory,
then SDL game controller mappings will be loaded from it.
There is an officially endorsed community sourced database in
https://github.com/gabomdq/SDL_GameControllerDB
This feature allows us to work around analog stick range issues at the
intercardinal directions in certain titles (e.g. Rockman DASH 2) caused
by modern controllers having a tighter logical range of reporting than
PS1 analog controllers.