GBA link support

[simeononsecurity]

Seems there was some politics involved with some suggested changes.
Linux GBA link support as well as compatibility for libretro needs to be added.
This feature is critical to the community. Who wants to play any of these games if we're forced to never play with anyone else?
It was originally submitted in 2014 and seemingly no official efforts have been made to fix the issue and previous tickets have been closed preemptively. I get this is a major effort to enable this feature set. But, if it's a legitimate issue that still exists and you're waiting on a dependency, you can't just close the issue. Leave the ticket open so that it can be tracked.

visualboyadvance-m/visualboyadvance-m#356
libretro/vbam-libretro#14
#1124