Text: Fix segfault when a test is re-executed.

It happens in the text append test. One of the internal pointers was
pointing to freed memory.

src/bin/textblock_text_append.c

@@ -106,6 +106,7 @@ static void _setup(void)
 static void _cleanup(void)
 {
    eo_del(o_text);
+   o_text = NULL;
 }
 
 /* loop - do things */
@@ -118,6 +119,7 @@ static void _loop(double t, int f)
    evas_textblock_cursor_char_delete(cur);
 
    evas_textblock_cursor_paragraph_char_first(cur);
+   if (!o_text) cur2 = NULL;
    if (!cur2)
      {
         eo_do(o_text, cur2 = evas_obj_textblock_cursor_new());