Util: Get rid of _to16Bit

[meleu]

This is the equivalent to this commit from upstream.

It solves the undefined reference to '_to16Bit' I reported in #69 .

This solution was pointed out by @endrift in this comment.

One step at a time and soon we will have mgba on PS Vita. :-)

[meleu]

By the way, this PR solves the problems to compile mgba for Vita (the exact description of the issue #69 ), but after compiling and installing, RetroArch crashes at launching on Vita. I think we should leave that issue open just to not lose the conversation about "making mgba core work on PS Vita".

[sergiobenrocha2]

You can use the command git cherry-pick instead, to backport stuff like that

[meleu]

@sergiobenrocha2 oh, thanks. Every time is time to learn a new git trick. I thought that "cherry-pick" was a slang to "carefully pick what changed here and do the equivalent there". :-)

Anyway I compiled here and everything compiled fine. Now I will try to debug/check what's causing the crash on Vita.

Best regards!