Memory leak in keyboard variables?

[Chong Yidong <cyd@stupidchicken.com>]

I've been looking into the memory leak that occurs when terminal frames
are killed.  From Markus Triska's recipe:

 emacs -nw -f server-start
 for i in {1..100}; do emacsclient -t -e "(save-buffers-kill-terminal)"; done 

I think at least some of this leakage is due to unfreed Lisp objects.
For instance, this code in xterm.el leads to ~ 1000 unfreed conses per
terminal created and destroyed:

   (let ((map (copy-keymap xterm-function-map)))
      ...
      (set-keymap-parent map (keymap-parent input-decode-map))
      (set-keymap-parent input-decode-map map)))

Now, input-decode-map is defined in keyboard.c, using DEFVAR_KBOARD.  It
is a Lisp_Misc_Kboard_Objfwd object, and if I'm not mistaken, such
objects are not garbage-collected.

When the terminal is killed, are its keyboard's Lisp_Misc_Kboard_Objfwd
objects freed?  As far as I can tell, they are not freed.  But I am no
expert in this part of the code, so maybe someone else can clue me in.