bug#13449: 24.3.50; Perl mode composed symbols not visible

[Richard Copley <rcopley@gmail.com>]

When I visit a Perl source file from `emacs -Q', the Unicode
replacements for `=>' and "::" are not visible (they appear the same as
a single space character would). The `->' character is not
affected. This happens on Windows XP. I think it does not happen on
Windows 8 or Linux (but I will check when I get the chance). Doing "M-x
set-variable perl-prettify-symbols RET nil RET" (or using
customize-variable) doesn't cause the character(s) to redisplay
differently (even if I kill the buffer and visit the file again), but if
I do (setq perl-prettify-symbols nil) from `emacs -Q' and then visit
the Perl source file, the non-prettified versions are visible.

In GNU Emacs 24.3.50.1 (i386-mingw-nt5.1.2600)
 of 2012-11-12 on 57172UHB
Bzr revision: 110872
vincentb1@users.sourceforge.net-20121112055353-v0t5ytiafc4327c8
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --enable-checking --cflags
 -fno-omit-frame-pointer -L c:/gnuwin32/lib -I c:/gnuwin32/include'

Important settings:
  value of $EMACSDATA: c:/Emacs/emacs-110872/etc
  value of $EMACSDOC: c:/Emacs/emacs-110872/etc
  value of $EMACSLOADPATH:
c:/Emacs/emacs-110872/site-lisp;c:/Emacs/emacs-110872/../site-lisp;c:/Emacs/emacs-110872/lisp;c:/Emacs/emacs-110872/leim
  value of $EMACSPATH: c:/Emacs/emacs-110872/bin
  value of $LANG: ENG
  locale-coding-system: cp1252
  default enable-multibyte-characters: t

Major mode: Perl

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
M-x s e t SPC v a r i a b l e <return> p e r l - p
r e t t i f y - s y m b o l s <return> n i l <return>
C-x k <return> C-x C-f b u i l d . p l <return> <down-mouse-1>
<mouse-1> C-x = M-x r e p o r t - e m a c s - b u g
<return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Char: = (61, #o75, #x3d) point=388 of 13354 (3%) column=34

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils cus-edit easymenu cus-start cus-load wid-edit
help-fns perl-mode time-date tooltip ediff-hook vc-hooks lisp-float-type
mwheel dos-w32 ls-lisp w32-common-fns disp-table w32-win w32-vars
tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment
lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar
mouse jit-lock font-lock syntax facemenu font-core frame cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
minibuffer button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process w32 multi-tty
emacs)