[client] resources: clean up icon handling

This commit turns the icon handling into using a macro so we don't need to do
weird conversions from unsigned long (needed by X11) to uint32_t (needed by
Wayland).

Also simplified the error handling path on Wayland.

client/displayservers/X11/x11.c

@@ -52,6 +52,7 @@
 #endif
 
 #include "app.h"
+#include "common/array.h"
 #include "common/debug.h"
 #include "common/time.h"
 #include "common/event.h"
@@ -80,6 +81,10 @@ enum {
   MWM_FUNC_CLOSE        = (1L << 5)
 };
 
+static const unsigned long icondata[] = {
+  LG_ICON_WIDTH, LG_ICON_HEIGHT, LG_ICON_PIXELS,
+};
+
 // forwards
 static void x11SetFullscreen(bool fs);
 static int  x11EventThread(void * unused);
@@ -617,7 +622,7 @@ static bool x11Init(const LG_DSInitParams params)
     32,
     PropModeReplace,
     (unsigned char *)icondata,
-    icondataSize / sizeof(icondata[0])
+    ARRAY_LENGTH(icondata)
   );
 
   /* create the blank cursor */