edc_editor: fix segfault on last character undo.

Summary:
In case when undone character(s) in entry, was call updating syntax highlight. If entry is empty, then pointer of text  didn't cleared and it was cause segfault in evas_textblock module.
@fix Fixes T1480

Reviewers: Hermet

Subscribers: kfesyna

Projects: #enventor

Maniphest Tasks: T1480

Differential Revision: https://phab.enlightenment.org/D1272

src/bin/edc_editor.c

@@ -205,7 +205,7 @@ syntax_color_full_update(edit_data *ed, Eina_Bool thread)
 
    if (thread)
      {
-        syntax_color_td *td = malloc(sizeof(syntax_color_td));
+        syntax_color_td *td = calloc(1, sizeof(syntax_color_td));
         if (!td)
           {
              EINA_LOG_ERR("Failed to allocate Memory!");