bug#12868: global keymap preceeds input-decode-map

[Stefan Guath]

emacs-version: GNU Emacs 24.2.1 (x86_64-apple-darwin, NS apple-appkit-1038.36) 
of 2012-08-27 on bob.porkrind.org

To trigger bug:
emacs -nw -Q
(defun foo () (interactive) (message "foo"))
(global-set-key "\M-O" 'foo)

Bug symptons:
Arrow keys now inserts A,B,C,D in buffer.

Suggested bug reason:
Arrow keys sends M-O A (up), M-O B (down) etc. These should be translated to 
function keys <up>, <down> etc in input-decode-map before any key lookup. 
Somehow, the binding of M-O in the global keymap takes precedence. This would 
be expected with local-function-key-map as described in 
http://www.gnu.org/software/emacs/manual/html_node/elisp/Translation-Keymaps.html
 , but not with input-decode-map.