(xw-color-values): Use CGFloat where appropriate.

src/nsfns.m

@@ -2224,7 +2224,7 @@ and GNUstep implementations ("distributor-specific release
      Lisp_Object color, frame;
 {
   NSColor * col;
-  float red, green, blue, alpha;
+  CGFloat red, green, blue, alpha;
 
   check_ns ();
   CHECK_STRING (color);