bug#19680: 24.4; option --no-bitmap-icon not working

[Glenn Morris <rgm@gnu.org>]

Preston Crow wrote:

> The command-line option "--no-bitmap-icon" used to turn off the bitmap
> icon, but after upgrading to the latest version, this option appears to
> be ignored.
>
> In GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.6)

I suspect the 2013-09-17 changes to x_iconify_frame etc.
The following lightly tested patch seemed to fix it for me.
Since this is a new, seemingly simple problem in 24.4 it might be good
to fix it for 24.5; ie quickly in emacs-24.

--- a/src/frame.h
+++ b/src/frame.h
@@ -1349,7 +1349,7 @@ x_set_bitmap_icon (struct frame *f)
 {
   Lisp_Object obj = assq_no_quit (Qicon_type, f->param_alist);
 
-  if (CONSP (obj))
+  if (CONSP (obj) && !NILP (XCDR (obj)))
     x_bitmap_icon (f, XCDR (obj));
 }