Make sure the tool-bar icons are found on the load-path.

diff --git a/mew-key.el b/mew-key.el
index 4b753f6..6a27090 100644
--- a/mew-key.el
+++ b/mew-key.el
@@ -627,6 +627,7 @@
 	    (throw 'loop (expand-file-name "etc" path)))))))
 
 (defvar mew-icon-directory (mew-which-mew-etc))
+(add-to-list 'load-path mew-icon-directory)
 
 (defvar mew-icon-separate nil)
 (defvar mew-icon-blank nil)