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");
609255e1344a328e360'>refs</a><a class='active' href='/guix/log/gnu/packages/patches/emacs-telega-test-env.patch'>log</a><a href='/guix/tree/gnu/packages/patches/emacs-telega-test-env.patch?id=ebd1ba713cbefc9ad5dac609255e1344a328e360'>tree</a><a href='/guix/commit/gnu/packages/patches/emacs-telega-test-env.patch?id=ebd1ba713cbefc9ad5dac609255e1344a328e360'>commit</a><a href='/guix/diff/gnu/packages/patches/emacs-telega-test-env.patch?id=ebd1ba713cbefc9ad5dac609255e1344a328e360'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/patches/emacs-telega-test-env.patch'>
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<tr><td><span title='2020-04-28 20:44:30 +0300'>2020-04-28</span></td><td><a href='/guix/commit/gnu/packages/patches/emacs-telega-test-env.patch?id=19e1f12ce420104451c16ab5412cb65cd8fe68cd'>gnu: emacs-telega: Test Emacs environment on startup.</a><span class='msg-avail'>...<span class='msg-tooltip'>Print a more helpful error message when someone attempts to run Telega on an
incompatible Emacs (e.g a 32-bit Emacs without wide ints).

* gnu/packages/patches/emacs-telega-test-env.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/emacs-xyz.scm (emacs-telega)[source]: Use it.

Signed-off-by: Efraim Flashner &lt;efraim@flashner.co.il&gt;
</span></span></td><td>Diego Nicola Barbato</td></tr>