Add automated checking for non-escaped --

This checks to see if any man output has [em] in it, as that will not
be correctly show in ASCII. Unfortunately the check will depend on
whether the other man check is done, but I didn't want to introduce
yet another short script for this (can be done, no issue).

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

autotools/check-man

 #!/bin/bash
 #
 
-# Copyright (C) 2010 Google Inc.
+# Copyright (C) 2010, 2012 Google Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -24,3 +24,6 @@ set -e
   man --warnings --encoding=utf8 --local-file "$1" 2>&1 >/dev/null | \
   grep -v -e "cannot adjust line" -e "can't break line" | \
   grep .
+
+! grep -F -q '\[em]' "$1" || \
+  { echo "Unescaped dashes found in $1, use \\-- instead of --" 1>&2; exit 1; }