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, 15 insertions, 12 deletions

diff --git a/man/systemd.netdev.xml b/man/systemd.netdev.xml
index 01c31c5ef5..6cd77abd04 100644
--- a/man/systemd.netdev.xml
+++ b/man/systemd.netdev.xml
@@ -1,6 +1,9 @@
 <?xml version='1.0'?> <!--*-nxml-*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+<!ENTITY % entities SYSTEM "custom-entities.ent" >
+%entities;
+]>
 
 <!--
   This file is part of systemd.
@@ -68,11 +71,11 @@
 
     <para>The <filename>.netdev</filename> files are read from the
     files located in the system network directory
-    <filename>/usr/lib/systemd/network</filename>, the volatile
+    <filename>&rootlibexecdir;/network</filename>, the volatile
     runtime network directory
     <filename>/run/systemd/network</filename> and the local
     administration network directory
-    <filename>/etc/systemd/network</filename>. All configuration files
+    <filename>&pkgsysconfdir;/network</filename>. All configuration files
     are collectively sorted and processed in lexical order, regardless
     of the directories in which they live. However, files with
     identical filenames replace each other. Files in
@@ -842,7 +845,7 @@
   <refsect1>
     <title>Example</title>
     <example>
-      <title>/etc/systemd/network/bridge.netdev</title>
+      <title>&pkgsysconfdir;/network/bridge.netdev</title>
 
       <programlisting>[NetDev]
 Name=bridge0
@@ -850,7 +853,7 @@ Kind=bridge</programlisting>
     </example>
 
     <example>
-      <title>/etc/systemd/network/vlan1.netdev</title>
+      <title>&pkgsysconfdir;/network/vlan1.netdev</title>
 
       <programlisting>[Match]
 Virtualization=no
@@ -863,7 +866,7 @@ Kind=vlan
 Id=1</programlisting>
     </example>
     <example>
-      <title>/etc/systemd/network/ipip.netdev</title>
+      <title>&pkgsysconfdir;/network/ipip.netdev</title>
       <programlisting>[NetDev]
 Name=ipip-tun
 Kind=ipip
@@ -875,7 +878,7 @@ Remote=192.169.224.239
 TTL=64</programlisting>
     </example>
     <example>
-      <title>/etc/systemd/network/tap.netdev</title>
+      <title>&pkgsysconfdir;/network/tap.netdev</title>
       <programlisting>[NetDev]
 Name=tap-test
 Kind=tap
@@ -885,7 +888,7 @@ MultiQueue=true
 PacketInfo=true</programlisting> </example>
 
     <example>
-      <title>/etc/systemd/network/sit.netdev</title>
+      <title>&pkgsysconfdir;/network/sit.netdev</title>
       <programlisting>[NetDev]
 Name=sit-tun
 Kind=sit
@@ -897,7 +900,7 @@ Remote=10.65.223.239</programlisting>
     </example>
 
     <example>
-      <title>/etc/systemd/network/gre.netdev</title>
+      <title>&pkgsysconfdir;/network/gre.netdev</title>
       <programlisting>[NetDev]
 Name=gre-tun
 Kind=gre
@@ -909,7 +912,7 @@ Remote=10.65.223.239</programlisting>
     </example>
 
     <example>
-      <title>/etc/systemd/network/vti.netdev</title>
+      <title>&pkgsysconfdir;/network/vti.netdev</title>
 
       <programlisting>[NetDev]
 Name=vti-tun
@@ -922,7 +925,7 @@ Remote=10.65.223.239</programlisting>
     </example>
 
     <example>
-      <title>/etc/systemd/network/veth.netdev</title>
+      <title>&pkgsysconfdir;/network/veth.netdev</title>
       <programlisting>[NetDev]
 Name=veth-test
 Kind=veth
@@ -932,7 +935,7 @@ Name=veth-peer</programlisting>
     </example>
 
     <example>
-      <title>/etc/systemd/network/dummy.netdev</title>
+      <title>&pkgsysconfdir;/network/dummy.netdev</title>
       <programlisting>[NetDev]
 Name=dummy-test
 Kind=dummy