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

--- geoclue-2.1.10/src/gclue-config.c	2015-04-07 09:50:07.721074380 +0200
+++ geoclue-2.1.10/src/gclue-config.c	2015-04-07 10:27:26.613171960 +0200
@@ -235,6 +235,11 @@
 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 == NULL)
+	  config_file_path = CONFIG_FILE_PATH;
 
         config->priv =
                 G_TYPE_INSTANCE_GET_PRIVATE (config,
@@ -242,7 +247,7 @@
                                             GClueConfigPrivate);
         config->priv->key_file = g_key_file_new ();
         g_key_file_load_from_file (config->priv->key_file,
-                                   CONFIG_FILE_PATH,
+                                   config_file_path,
                                    0,
                                    &error);
         if (error != NULL) {
s='sub right'></td></tr></table>
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<tr><td><span title='2018-01-10 23:40:35 +0100'>2018-01-10</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=721bdea50bd5d65b7a1be12f369d5dc6ab65b6b8'>gnu: libmtp: Update to 1.1.14.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-12-28 08:35:24 +0100'>2017-12-28</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=93e5c93e4c3ba60bfe277658b9656e2d9eb2d486'>gnu: Add python-hidapi.</a><span class='msg-avail'>...</span></td><td>Danny Milosavljevic</td></tr>
<tr><td><span title='2017-11-12 03:25:49 +0100'>2017-11-12</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=07cc9245e6def0060fd1b328c09f2637b4381530'>gnu: libusb-compat: Use the same home page as libusb.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-10-03 17:07:54 +0200'>2017-10-03</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=d109b1e85c5c1438e66dfc05ea4a018418edaf19'>Update e-mail for Theodoros Foradis.</a><span class='msg-avail'>...</span></td><td>Theodoros Foradis</td></tr>
<tr><td><span title='2017-09-04 00:10:59 -0400'>2017-09-04</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=d10092b849153dc27cfed0a9601fde6c7bdec918'>gnu: Put autoconf-related phases immediately after the 'unpack phase.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
<tr><td><span title='2017-07-20 00:54:52 +0200'>2017-07-20</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=05c88516955814ac61dc7578017e1976c43a1cd3'>gnu: Add libusb@0.1.</a><span class='msg-avail'>...</span></td><td>Jonathan Brielmaier</td></tr>
<tr><td><span title='2017-05-15 22:33:13 +0200'>2017-05-15</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=423b6840b3d7ada3b3c5fef7fdb64b8bbc1acb2b'>gnu: Add java-usb4java.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2017-05-15 22:33:13 +0200'>2017-05-15</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=18fe5ef1520ee085bf409ee983ed12baf20ea40e'>gnu: Add libusb4java.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2017-04-06 15:03:07 +0200'>2017-04-06</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=2c273a82f36260cbc68ce65b9f73e581eb471690'>gnu: libusb: Update to 1.0.21.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-04-06 14:58:05 +0200'>2017-04-06</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=05b662663d49883aa5b434c0ce94555ced70fed8'>gnu: libmtp: Update to 1.1.13 [security fixes].</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2016-11-09 21:24:44 +0100'>2016-11-09</span></td><td><a href='/guix/commit/gnu/packages/libusb.scm?id=28791c1c8d43e14878f8cc67a15b6036699ec252'>gnu: hidapi: Fix 'license'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>