9.5 make world failing due to sgml tools missing

The current HEAD of postgres in the git repo is not building when using
"make world". It's been like this for about a month or so that I've been
aware of. I didn't really need the world build so been making due without
it. At PGCon now, though, so asked Bruce and he said this error was due to
my not having the sgml tools installed, which should not be a requirement.

Brief part of the compile output is below with the error at the end. Full
output is attached.

[...]
sgml2xml:xml2.sgml:379:8:W: reference to internal SDATA entity "gt" not
allowed in XML
sgml2xml:oid2name.sgml:157:42:W: reference to internal SDATA entity "mdash"
not allowed in XML
sgml2xml:docguide.sgml:1053:0:W: reference to internal SDATA entity "lt"
not allowed in XML
sgml2xml:docguide.sgml:1053:61:W: reference to internal SDATA entity "gt"
not allowed in XML
'/usr/bin/perl' -p -e
's/\[(aacute|acirc|aelig|agrave|amp|aring|atilde|auml|bull|copy|eacute|egrave|gt|iacute|lt|mdash|nbsp|ntilde|oacute|ocirc|oslash|ouml|pi|quot|scaron|uuml)
*\]/\&\1;/gi;' \
-e '$_ .= qq{<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook
XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">\n}
if $. == 1;' \
<postgres.xmltmp > postgres.xml
rm postgres.xmltmp
/bin/sh ../../../config/missing xmllint --noout --valid postgres.xml
***
ERROR: `xmllint' is missing on your system.
***
make[3]: *** [man-stamp] Error 1
make[3]: Leaving directory `/home/keith/Repos/postgres/doc/src/sgml'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/keith/Repos/postgres/doc/src'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/keith/Repos/postgres/doc'
make: *** [world-doc-recurse] Error 2
--
Keith Fiske
Database Administrator
OmniTI Computer Consulting, Inc.
http://www.keithf4.com