Promote plugin loading issues to error logging level

If plugin loading fails, provide diagnostic output about it on default
verbosity level. Also provide failure reason (for example unmet dynamic
symbol dependencies) as made available from g_module_error().

mce-modules.c

@@ -172,15 +172,17 @@ gboolean mce_modules_init(void)
 			GModule *module;
 			gchar *tmp = g_module_build_path(path, modlist[i]);
 
-			mce_log(LL_DEBUG,
+			mce_log(LL_INFO,
 				"Loading module: %s from %s",
 				modlist[i], path);
 
 			if ((module = g_module_open(tmp, 0)) != NULL) {
 				/* XXX: check dependencies, conflicts, et al */
 				modules = g_slist_prepend(modules, module);
 			} else {
-				mce_log(LL_DEBUG,
+				const char *err = g_module_error();
+				mce_log(LL_ERR, "%s", err ?: "unknown error");
+				mce_log(LL_ERR,
 					"Failed to load module: %s; skipping",
 					modlist[i]);
 			}