[easytag] Fix undefined symbol when id3lib is not available

[David King <davidk src gnome org>]

commit 6aecd7451e3889c5f755736b427a478c93e9f5b2
Author: David King <amigadave amigadave com>
Date:   Fri Apr 22 15:48:18 2016 +0530

    Fix undefined symbol when id3lib is not available

 src/easytag.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/easytag.c b/src/easytag.c
index 776f690..fc26747 100644
--- a/src/easytag.c
+++ b/src/easytag.c
@@ -756,6 +756,7 @@ Write_File_Tag (ET_File *ETFile, gboolean hide_msgbox)
 
     if (!hide_msgbox)
     {
+#ifdef ENABLE_ID3LIB
         if (g_error_matches (error, ET_ID3_ERROR, ET_ID3_ERROR_BUGGY_ID3LIB))
         {
             msgdialog = gtk_message_dialog_new (GTK_WINDOW (MainWindow),
@@ -785,6 +786,7 @@ Write_File_Tag (ET_File *ETFile, gboolean hide_msgbox)
                                                       basename_utf8);
         }
         else
+#endif
         {
             msgdialog = gtk_message_dialog_new (GTK_WINDOW (MainWindow),
                                                 GTK_DIALOG_MODAL | GTK_DIALOG_DESTROY_WITH_PARENT,