Build fails without docbook-xsl

[usedbytes]

Building on Arch from https://aur.archlinux.org/packages/systemd-bootchart-git fails if docbook-xsl isn't installed. I guess it should be somehow flagged as a build dependency?

/usr/bin/xsltproc -o man/bootchart.conf.5 --nonet --xinclude --stringparam man.output.quietly 1 --stringparam funcsynopsis.style ansi --stringparam man.authors.section.enabled 0 --stringparam man.copyright.section.enabled 0 --stringparam systemd.version 231 --path './man:./man' ./man/custom-man.xsl man/bootchart.conf.xml
I/O error : Attempt to load network entity http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl
warning: failed to load external entity "http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"
compilation error: file ./man/custom-man.xsl line 27 element import
xsl:import : unable to load http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl
make[2]: *** [Makefile:1765: man/bootchart.conf.5] Error 5
make[1]: *** [Makefile:1309: all-recursive] Error 1
make: *** [Makefile:648: all] Error 2

Found a similar issue here with a fix: https://github.com/hughsie/appdata-tools/issues/10

[ycongal-smile]

FYI, the URL with the fix has been removed but is available on archive.org.

The gist of the fix is to install docbook-xsl or equivalent (works on my debian 10.1)

[treedavies]

Can the need for docbook be disabled from the build?