memleak: osmo_config_list_parse: getline() needs free also on error

Helps fix sanitizer build on debian 9.

Change-Id: Iddf0a6cc733cd81d5f6c1eb62fc079ad319db119
diff --git a/src/msgfile.c b/src/msgfile.c
index 278b9a7..1f11aa6 100644
--- a/src/msgfile.c
+++ b/src/msgfile.c
@@ -119,9 +119,10 @@
 	line = NULL;
         while (getline(&line, &n, file) != -1) {
 		handle_line(entries, line);
-		free(line);
-		line = NULL;
 	}
+	/* The returned getline() buffer needs to be freed even if it failed. It can simply re-use the
+	 * buffer that was allocated on the first call. */
+	free(line);
 
 	fclose(file);
 	return entries;