+++ This bug was initially created as a clone of Bug #553560 +++

Please describe the problem:
xsl:sort lang="eo"  is not sorting correct because it's not using eo locale.

Steps to reproduce:
1. l.xml:
<?xml version="1.0" encoding="UTF-8"?> 
<?xml-stylesheet type="text/xsl" href="l.xsl"?>
<lingvoj>
  <lingvo>jida</lingvo>
  <lingvo>joruba</lingvo>
  <lingvo>ĝuanga</lingvo>
  <lingvo>ĉina</lingvo>
  <lingvo>zulua</lingvo>
</lingvoj>

2. l.xsl:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method='text' encoding='UTF-8'/>
<xsl:template match="/">Lingvoj:<xsl:for-each select="lingvoj/lingvo">
      <xsl:sort lang="eo-us" select="."/>
        <xsl:text>&#10;&#13;      </xsl:text>
        <xsl:value-of select="."/>
      </xsl:for-each>
      <xsl:text>&#10;&#13;</xsl:text>
</xsl:template>
</xsl:stylesheet>

3.
xsltproc l.xsl l.xml

Actual results:
Lingvoj:
      jida
      joruba
      zulua
      ĉina
      ĝuanga

Expected results:
Lingvoj:
      ĉina
      ĝuanga
      jida
      joruba
      zulua


Does this happen every time?
Yes

Other information:
GNU libc supports Esperanto "eo" as locale, with your patch it works fine.
But GNU libc does not distribute eo locale.
It is missing in 
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/localedata/locales/?cvsroot=glibc
But there is "i18n" (without a region).
And localedef has no problem.

I will ask to put eo in glibc, that will be the best solution.