Fix colored rectangle color.

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@15067 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/shaders/coloredquad.frag

@@ -3,5 +3,5 @@ uniform ivec4 color;
 
 void main()
 {
-	gl_FragColor = color;
-}
+	gl_FragColor = vec4(color) / 255.;
+}