man: generate configured paths in manpages

In particular, use /lib/systemd instead of /usr/lib/systemd in distributions
like Debian which still have not adopted a /usr merge setup.

Use XML entities from man/custom-entities.ent to replace configured paths while
doing XSLT processing of the original XML files. There was precedent of some
files (such as systemd.generator.xml) which were already using this approach.

This addresses most of the (manual) fixes from this patch:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220

The idea of using generic XML entities was presented here:
http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html

This patch solves almost all the issues, with the exception of:
- Path to /bin/mount and /bin/umount.
- Generic statements about preference of /lib over /etc.

These will be handled separately by follow up patches.

Tested:
- With default configure settings, ran "make install" to two separate
  directories and compared the output to confirm they matched exactly.
- Used a set of configure flags including $CONFFLAGS from Debian:
  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules
  Installed the tree and confirmed the paths use /lib/systemd instead of
  /usr/lib/systemd and that no other unexpected differences exist.
- Confirmed that `make distcheck` still passes.

1 files changed, 6 insertions, 3 deletions

diff --git a/man/standard-conf.xml b/man/standard-conf.xml
index 004f53f70c..123877a0a5 100644
--- a/man/standard-conf.xml
+++ b/man/standard-conf.xml
@@ -1,6 +1,9 @@
 <?xml version="1.0"?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
 <!DOCTYPE refsection PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
-          "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
+          "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % entities SYSTEM "custom-entities.ent" >
+%entities;
+]>
 
 <refsection>
   <refsection id='confd'>
@@ -39,14 +42,14 @@
     <para>Default configuration is defined during compilation, so a
     configuration file is only needed when it is necessary to deviate
     from those defaults. By default the configuration file in
-    <filename>/etc/systemd/</filename> contains commented out entries
+    <filename>&pkgsysconfdir;/</filename> contains commented out entries
     showing the defaults as a guide to the administrator. This file
     can be edited to create local overrides.
     </para>
 
     <para>When packages need to customize the configuration, they can
     install configuration snippets in
-    <filename>/usr/lib/systemd/*.conf.d/</filename>. Files in
+    <filename>&rootlibexecdir;/*.conf.d/</filename>. Files in
     <filename>/etc/</filename> are reserved for the local
     administrator, who may use this logic to override the
     configuration files installed by vendor packages. The main