* MODULES.html.sh: Fix sed-script shell quoting and locale issues.

* MODULES.html.sh: Fix sed-script shell quoting and locale issues.

(func_module): Replace foo=` ... sed -e COMPLICATED ... ` with
bar=COMPLICATED; foo=` ... sed -e "$bar" ... ` when COMPLICATED
contains (possibly-quoted) backslashes.  This should avoid
all-too-common shell bugs if COMPLICATED contains backslashes in
the "wrong" places.  Reported by David Evans in
<http://lists.gnu.org/archive/html/bug-gnulib/2011-11/msg00013.html>.
When 'sed' uses character ranges like A-Z, invoke it in the C locale,
because we want ASCII ranges.  Is there some reason we don't use
the C locale everywhere in this script?
(func_module, top level): Avoid unwanted pathname expansion when
$repo_url_prefix or $repo_url_suffix_repl contain shell
metacharacters like '?' and '*'.