N3DS support

[TheMode]

devkitPro API is I believe UNIX-compatible, however having a compile error due to #include <ifaddrs.h>

From what I understand, local address that be retrieved through SOCU_GetIPInfo().

The n3ds threads are also cooperative, unsure if this is relevant here.

[icculus]

I probably can't work on this, but I'll accept a PR if someone else does it!