libxml2 2.15.1
=
https://github.com/GNOME/libxml2/archive/refs/tags/v2.15.1.tar.gz  

``` sh *** build ***
libtoolize
./autogen.sh
./configure --prefix=/pkg/gnu/libxml2
make -j$(nproc)
make install
```

``` sh *** config ***
mkdir -p /pkg/gnu/libxml2/etc/xml
cat > /pkg/gnu/libxml2/etc/xml/catalog <<'EOF'
<?xml version="1.0"?>
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer="public">

    <!-- ========== DocBook DTD 4.x ========== -->
    <rewriteURI uriStartString="http://www.oasis-open.org/docbook/xml/4.1.2/"
            rewritePrefix="file:///pkg/gnu/docbook4-xml/share/xml/docbook/dtd/4.5/"/>
    <rewriteURI uriStartString="https://www.oasis-open.org/docbook/xml/4.1.2/"
            rewritePrefix="file:///pkg/gnu/docbook4-xml/share/xml/docbook/dtd/4.5/"/>
  
    <!-- ========== DocBook Schema 5.x ========== -->
    <delegateURI uriStartString="http://docbook.org/xml/5.0/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>
    <delegateURI uriStartString="http://docbook.org/xml/5.1/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>
    <delegateURI uriStartString="http://docbook.org/xml/5.2/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>
    <delegateURI uriStartString="https://docbook.org/xml/5.0/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>
    <delegateURI uriStartString="https://docbook.org/xml/5.1/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>
    <delegateURI uriStartString="https://docbook.org/xml/5.2/"
            catalog="/pkg/gnu/docbook5-xml/share/xml/docbook/schema/5.2/catalog.xml"/>

    <!-- ========== DocBook XSLT 1.0 (namespace) ========== -->
    <delegateURI uriStartString="http://docbook.sourceforge.net/release/xsl/"
            catalog="/pkg/gnu/docbook-xslt1/etc/xml/catalog"/>
    
    <!-- ========== DocBook XSLT 1.0 (non-namespace) ========== -->
    <delegateURI uriStartString="http://docbook.sourceforge.net/release/xsl/non-ns/"
            catalog="/pkg/gnu/docbook-xslt1-nons/etc/xml/catalog"/>
    
    <!-- ========== DocBook XSLT 2.0+ (xslTNG) ========== -->
    <delegateURI uriStartString="https://codeberg.org/DocBook/xslTNG/"
            catalog="/pkg/gnu/docbook-xslt/etc/xml/catalog"/>
    <delegateURI uriStartString="https://docbook.org/xslTNG/"
            catalog="/pkg/gnu/docbook-xslt/etc/xml/catalog"/>

</catalog>
EOF

mkdir -p /pkg/gnu/s6/etc/envdir
echo "/pkg/gnu/libxml2/etc/xml/catalog" > /pkg/gnu/s6/etc/envdir/XML_CATALOG_FILES
```