Bug#820165: RFS: libretro-genesisplusgx/1.7.4+git20160330 [ITP]

[Sergio benjamim Rocha filho]

Hi Piccoro,
MAME changed its license, but Genesis Plus GX uses the old one. Also, it's 
based on some portions of old mame code: 
https://github.com/ekeeke/Genesis-Plus-GX/blob/master/LICENSE.txt#L7
 
regards,sergio-br2