Update to v094r28 release.

byuu says:

This WIP substantially restructures the ruby API for the first time
since that project started.

It is my hope that with this restructuring, destruction of the ruby
objects should now be deterministic, which should fix the crashing on
closing the emulator on Linux. We'll see I guess ... either way, it
removed two layers of wrappers from ruby, so it's a pretty nice code
cleanup.

It won't compile on Windows due to a few issues I didn't see until
uploading the WIP, too lazy to upload another. But I fixed all the
compilation issues locally, so it'll work on Windows again with the next
WIP (unless I break something else.)

(Kind of annoying that Linux defines glActiveTexture but Windows
doesn't.)

ucontext.c

@@ -18,6 +18,8 @@
 
 #define LIBCO_C
 #include "libco.h"
+
+#define _BSD_SOURCE
 #include <stdlib.h>
 #include <ucontext.h>