[GME Input] Correct old comment in the code

There has been an API in GME to detect tracks ending for quite some time
now, and this just adds a little bit to the existing comment, which
previously noted that there was no way to detect if a track had ended,
which may have been true several major versions of GME long past.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Plugins/GME/GameDecoder.m

@@ -197,6 +197,7 @@ gme_err_t readCallback(void *data, void *out, int count) {
 	// Some formats support length, but we'll add that in the future.
 	//(From gme.txt) If track length, then use it. If loop length, play for intro + loop * 2. Otherwise, default to 2.5 minutes
 	// GME will always generate samples. There's no real EOS.
+	// Addendum: The above gme_track_ended() call has been in place for years now
 
 	[chunk assignSamples:sampleBuffer frameCount:frames];