Add $EUDEV_RULES_DIRECTORY to the list of rules directories.

The old udev 182 supported $UDEV_CONFIG_FILE, which in turn allowed
the search path to be customized, but eudev no longer has this, hence
this hack.

--- eudev-3.1.5/src/udev/udev-rules.c	2015-10-13 06:22:14.000000000 +0800
+++ eudev-3.1.5/src/udev/udev-rules.c	2015-10-16 20:45:38.491934336 +0800
@@ -47,15 +47,11 @@
         };
 };
 
-static const char* const rules_dirs[] = {
+static const char* rules_dirs[] = {
         UDEV_CONF_DIR "/rules.d",
         UDEV_RULES_DIR,
-        UDEV_ROOT_RUN "/udev/rules.d",
         UDEV_LIBEXEC_DIR "/rules.d",
-#ifdef HAVE_SPLIT_USR
-        "/lib/udev/rules.d",
-        "/usr/lib/udev/rules.d",
-#endif
+        NULL,			/* placeholder for $EUDEV_RULES_DIRECTORY */
         NULL};
 
 struct udev_rules {
@@ -1704,6 +1700,9 @@
 
         udev_rules_check_timestamp(rules);
 
+        /* Allow the user to specify an additional rules directory.  */
+        rules_dirs[3] = getenv("EUDEV_RULES_DIRECTORY");
+
         r = conf_files_list_strv(&files, ".rules", NULL, rules_dirs);
         if (r < 0) {
                 log_error_errno(r, "failed to enumerate rules files: %m");
e' href='/guix/log/gnu/services/telephony.scm'>log</a><a href='/guix/tree/gnu/services/telephony.scm?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>tree</a><a href='/guix/commit/gnu/services/telephony.scm?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>commit</a><a href='/guix/diff/gnu/services/telephony.scm?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/services/telephony.scm'>
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<div class='path'>path: <a href='/guix/log/?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>root</a>/<a href='/guix/log/gnu?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>gnu</a>/<a href='/guix/log/gnu/services?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>services</a>/<a href='/guix/log/gnu/services/telephony.scm?id=85060391ba1878e1e437a7dbdb59561d37d2f00d'>telephony.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/services/telephony.scm?id=85060391ba1878e1e437a7dbdb59561d37d2f00d&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-10-07 12:41:06 -0400'>2023-10-07</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=00a28bc435606dc98925fbae1ebe314881f35c90'>services: configuration: Add some commonly used predicates.</a><span class='msg-avail'>...</span></td><td>Bruno Victal</td></tr>
<tr><td><span title='2023-10-07 12:41:05 -0400'>2023-10-07</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=a7994ed58dc1ac3b57aa2df8508f05fd0748b3e0'>services: configuration: Use transducers within serialize-configuration.</a><span class='msg-avail'>...</span></td><td>Bruno Victal</td></tr>
<tr><td><span title='2023-02-08 09:36:26 -0500'>2023-02-08</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=aef75942fc24fdb753978848b5471c5da21f23b7'>gnu: libjami: Move jamid daemon to a "bin" output.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-09-23 23:56:16 -0400'>2022-09-23</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=effdc6c83e7000bf062526f4256de69899e13b40'>services: jami-service-type: Streamline stop slot.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-08-25 00:10:32 -0400'>2022-08-25</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=ee08277a70d29b6d707524a4e17620f50b87adf4'>services: Use the new maybe/unset API.</a><span class='msg-avail'>...</span></td><td>Attila Lendvai</td></tr>
<tr><td><span title='2022-08-01 12:49:35 -0400'>2022-08-01</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=a2b89a3319dc1d621c546855f578acae5baaf6da'>services: configuration: Step back from *unspecified*.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-06-15 00:25:21 +0200'>2022-06-15</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=8cb1a49a3998c39f315a4199b7d4a121a6d66449'>services: configuration: Use *unspecified* instead of 'disabled.</a><span class='msg-avail'>...</span></td><td>Attila Lendvai</td></tr>
<tr><td><span title='2022-06-10 23:52:34 -0400'>2022-06-10</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=8649ac5eaa0447a766b18550787b60639e57a7fb'>services: jami-configuration: Rename 'jamid' field to 'libjami'.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-06-10 23:52:33 -0400'>2022-06-10</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=85b4dabd94d53f8179f31a42046cd83fc3a352fc'>services: jami: Modernize to adjust to Shepherd 0.9+ changes.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-04-12 20:32:32 +0200'>2022-04-12</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=42679e3f81a0fa61e225b1f6aa0e80e39625372f'>services: Replace murmur-service-type with mumble-server-service-type.</a><span class='msg-avail'>...</span></td><td>Liliana Marie Prikler</td></tr>
<tr><td><span title='2022-03-24 12:45:48 +0100'>2022-03-24</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=8044a1fec91e91b7cc45e3c486433e8a0a1ca2d5'>services: murmur: Fix server program name.</a><span class='msg-avail'>...</span></td><td>fesoj000</td></tr>
<tr><td><span title='2022-01-13 00:57:52 -0500'>2022-01-13</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=374fea0f3bc8035f626cb29e6045130df9ffdaf8'>services: Adjust the jami service for the upgraded jami.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2021-11-30 01:08:55 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/services/telephony.scm?id=892f1b7273d57b25940700877a02618fe826cc08'>services: Accept &lt;inferior-package&gt;s in lieu of &lt;package&gt;s.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>