Bug#911328: add .libretro metadata for better integration with gnome-games

[Patrick Ammann]

Package: libretro-desmume
Version: 0.9.11+git20160819+dfsg1-1


Please consider adding .libretro metadata for better integration with 
gnome-games.


See 
https://gitlab.gnome.org/GNOME/gnome-games/blob/master/flatpak/libretro-cores/desmume2015.libretro, 
Adapted for Debian (package name without 2015):
<snip>
[Libretro]
Type=Emulator
Version=1.0
Name=DeSmuME
Module=desmume_libretro.so
LibretroVersion=1
Authors=YopYop156;Zeromus;
License=GPL-2.0+;

[Platform:NintendoDS]
MimeType=application/x-nintendo-ds-rom;
</snip>

The file desmume.libretro is expected to be here 
"/usr/lib/x86_64-linux-gnu/libretro/"


Thanks,
Patrick