trunk r117870 -> emacs-24

[Dmitry Antipov <dmantipov@yandex.ru>]

Please consider changes from trunk revision 117870 for emacs-24 branch.
Without that, the latter is not immune against the following crashes
(64-bit only):

;; crash - overflow in font_parse_family_registry
(defun oops0 ()
   (let* ((size 2200000000)
          (s (make-string size 97)))
     (aset s 0 42)
     (aset s 1000 45)
     (x-family-fonts s)))

;; crash - overflow in make_temp_name
(defun oops1 ()
   (make-temp-name (make-string 2200000000 97)))

Dmitry