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");
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<div class='path'>path: <a href='/guix/commit/?id=8680eff30d6b41993dde8e5c03ec184475889820'>root</a>/<a href='/guix/commit/gnu?id=8680eff30d6b41993dde8e5c03ec184475889820'>gnu</a>/<a href='/guix/commit/gnu/packages?id=8680eff30d6b41993dde8e5c03ec184475889820'>packages</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='8680eff30d6b41993dde8e5c03ec184475889820'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;</td><td class='right'>2020-01-18 21:21:30 +0100</td></tr>
<tr><th>committer</th><td>Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;</td><td class='right'>2020-02-22 23:51:54 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/guix/commit/gnu/packages?id=8680eff30d6b41993dde8e5c03ec184475889820'>8680eff30d6b41993dde8e5c03ec184475889820</a> (<a href='/guix/patch/gnu/packages?id=8680eff30d6b41993dde8e5c03ec184475889820'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/guix/tree/?id=8680eff30d6b41993dde8e5c03ec184475889820'>9d1e10983ee546d7047d0ffee765050dbce58a87</a> /<a href='/guix/tree/gnu/packages?id=8680eff30d6b41993dde8e5c03ec184475889820'>gnu/packages</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/guix/commit/gnu/packages?id=414b8d9e499470dcfaadb518d36529a1627c2a72'>414b8d9e499470dcfaadb518d36529a1627c2a72</a> (<a href='/guix/diff/gnu/packages?id=8680eff30d6b41993dde8e5c03ec184475889820&amp;id2=414b8d9e499470dcfaadb518d36529a1627c2a72'>diff</a>)</td></tr><tr><th>download</th><td colspan='2' class='oid'><a href='/guix/snapshot/guix-8680eff30d6b41993dde8e5c03ec184475889820.tar.gz'>guix-8680eff30d6b41993dde8e5c03ec184475889820.tar.gz</a><br/><a href='/guix/snapshot/guix-8680eff30d6b41993dde8e5c03ec184475889820.zip'>guix-8680eff30d6b41993dde8e5c03ec184475889820.zip</a><br/></td></tr></table>
<div class='commit-subject'>gnu: python-singledispatch: Use HTTPS home page.</div><div class='commit-msg'>* gnu/packages/python-xyz.scm (python-singledispatch)[home-page]: Use HTTPS.
</div><div class='diffstat-header'><a href='/guix/diff/?id=8680eff30d6b41993dde8e5c03ec184475889820'>Diffstat</a> (limited to 'gnu/packages')</div><table summary='diffstat' class='diffstat'>