Fix sorting of indexed palettes

Author: Rangi42

src/gfx/main-495e5436.o.tmp

@@ -24,11 +24,12 @@ void sortIndexed(
 		);
 	};
 
-	for (Palette &pal : palettes) {
+	for (size_t palID = 0; palID < palettes.size(); ++palID) {
+		Palette &pal = palettes[palID];
 		std::sort(RANGE(pal), [&](uint16_t lhs, uint16_t rhs) {
 			// Iterate through the PNG's palette, looking for either of the two
 			for (int i = 0; i < palSize; ++i) {
-				uint16_t color = pngToRgb(i).cgbColor();
+				uint16_t color = pngToRgb((palID * 4 + i) % palSize).cgbColor();
 				if (color == Rgba::transparent) {
 					continue;
 				}