cgit: trying to install the manpage

Still fails:

  a2x: ERROR: "xsltproc"  --stringparam callout.graphics 0 --stringparam navig.graphics 0 --stringparam admon.textlabel 1 --stringparam admon.graphics 0 "/nix/store/by6h65klr7brgvf0474z21x1ykcdwhym-asciidoc-8.6.8/etc/asciidoc/docbook-xsl/manpage.xsl" "/tmp/nix-build-cgit-0.9.2.drv-0/cgit-0.9.2/cgitrc.5.xml" returned non-zero exit status 5