Use a non-recursive replace function when the parser supports it.

https://bugs.gnu.org/29782
https://bugzilla.samba.org/show_bug.cgi?id=9515
https://bugzilla.gnome.org/show_bug.cgi?id=736077 (for xsltproc)

Patch copied from Debian:
https://anonscm.debian.org/cgit/collab-maint/docbook-xsl.git/tree/debian/patches/765567_non-recursive_string_subst.patch

Description: use EXSLT "replace" function when available
 A recursive implementation  of string.subst is problematic,
 long strings with many matches will cause stack overflows.
Author: Peter De Wachter <pdewacht@gmail.com>
Bug-Debian: https://bugs.debian.org/750593

--- a/lib/lib.xsl
+++ b/lib/lib.xsl
@@ -10,7 +10,10 @@
      This module implements DTD-independent functions
 
      ******************************************************************** -->
-<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+                xmlns:str="http://exslt.org/strings"
+                exclude-result-prefixes="str"
+                version="1.0">
 
 <xsl:template name="dot.count">
   <!-- Returns the number of "." characters in a string -->
@@ -56,6 +59,9 @@
   <xsl:param name="replacement"/>
 
   <xsl:choose>
+    <xsl:when test="function-available('str:replace')">
+      <xsl:value-of select="str:replace($string, string($target), string($replacement))"/>
+    </xsl:when>
     <xsl:when test="contains($string, $target)">
       <xsl:variable name="rest">
         <xsl:call-template name="string.subst">
log/gnu/packages/tryton.scm'>
<input type='hidden' name='id' value='897186c1554e18a187429683d2eafdbfc0caac96'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=897186c1554e18a187429683d2eafdbfc0caac96'>root</a>/<a href='/guix/log/gnu?id=897186c1554e18a187429683d2eafdbfc0caac96'>gnu</a>/<a href='/guix/log/gnu/packages?id=897186c1554e18a187429683d2eafdbfc0caac96'>packages</a>/<a href='/guix/log/gnu/packages/tryton.scm?id=897186c1554e18a187429683d2eafdbfc0caac96'>tryton.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/tryton.scm?id=897186c1554e18a187429683d2eafdbfc0caac96&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-01-15 20:36:34 +0100'>2020-01-15</span></td><td><a href='/guix/commit/gnu/packages/tryton.scm?id=55e1475cb58c1b9535b35f8bdb157b1435c54755'>gnu: python-lxml: Move to (gnu packages xml).</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/python-xyz.scm (python-lxml): Move from here ...
* gnu/packages/xml.scm (python-lxml): ... to here.
* gnu/packages/django.scm, gnu/packages/drones.scm,
gnu/packages/libreoffice.scm, gnu/packages/nutrition.scm,
gnu/packages/openstack.scm, gnu/packages/pulseaudio.scm,
gnu/packages/python-science.scm, gnu/packages/tryton.scm,
gnu/packages/wireservice.scm: Adjust module imports.
</span></span></td><td>Marius Bakke</td></tr>