[easytag] Simplify invariant checks with et_str_empty()

[David King <davidk src gnome org>]

commit f18a548b5ae0f705a82db1b4da690fb6566191ba
Author: David King <amigadave amigadave com>
Date:   Fri Nov 13 18:59:35 2015 +0000

    Simplify invariant checks with et_str_empty()

 src/file_list.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/file_list.c b/src/file_list.c
index 4d79b43..5c54873 100644
--- a/src/file_list.c
+++ b/src/file_list.c
@@ -1206,8 +1206,8 @@ et_file_list_update_directory_name (GList *file_list,
     gchar *old_path_tmp;
 
     g_return_if_fail (file_list != NULL);
-    g_return_if_fail (old_path != NULL && *old_path != '\0');
-    g_return_if_fail (new_path != NULL && *new_path != '\0');
+    g_return_if_fail (!et_str_empty (old_path));
+    g_return_if_fail (!et_str_empty (new_path));
 
     /* Add '/' to end of path to avoid ambiguity between a directory and a
      * filename... */