Allow the configuration file to be specified via an environment variable.

diff --git a/src/gclue-config.c b/src/gclue-config.c
index 7ab2a67..e41f3df 100644
--- a/src/gclue-config.c
+++ b/src/gclue-config.c
@@ -332,6 +332,11 @@ static void
 gclue_config_init (GClueConfig *config)
 {
         GError *error = NULL;
+	const char *config_file_path;
+
+	config_file_path = g_getenv ("GEOCLUE_CONFIG_FILE");
+	if (!config_file_path)
+            config_file_path = CONFIG_FILE_PATH;
 
         config->priv = gclue_config_get_instance_private(config);
         config->priv->key_file = g_key_file_new ();
@@ -341,7 +346,7 @@ gclue_config_init (GClueConfig *config)
                                    &error);
         if (error != NULL) {
                 g_critical ("Failed to load configuration file '%s': %s",
-                            CONFIG_FILE_PATH, error->message);
+                            config_file_path, error->message);
                 g_error_free (error);
 
                 return;
ght'></td></tr></table>
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<tr><td><span title='2019-03-13 23:12:43 +0100'>2019-03-13</span></td><td><a href='/guix/commit/doc/images/installer-resume.png?id=e1c15e8b8e25e14c253ff1212e289565736f6ea7'>doc: Document the graphical installer some more.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Preparing for Installation): Rewrite to specify the two
installation modes.
(Guided Graphical Installation): New node.
(Manual Installation): New node, with the former sections.
(After System Installation): New node.
* doc/images/installer-network.png, doc/images/installer-partitions.png,
doc/images/installer-resume.png: New files.
* doc/local.mk (dist_infoimage_DATA): Add them.
</span></span></td><td>Ludovic Courtès</td></tr>