TextBlock: fix porting to Eolian.

evas_object_text_clear was no more defined in the headers. Since the
function code is not generated by Eolian, the declaration in the headers
has to be done manually too.

src/lib/evas/Evas_Legacy.h

@@ -1333,6 +1333,15 @@ EAPI char                                    *evas_textblock_text_markup_to_utf8
  */
 EAPI char                                    *evas_textblock_text_utf8_to_markup(const Evas_Object *obj, const char *text) EINA_WARN_UNUSED_RESULT EINA_MALLOC;
 
+/**
+ * Clear the textblock object.
+ * @note Does *NOT* free the Evas object itself.
+ *
+ * @param obj the object to clear.
+ * @return nothing.
+ */
+EAPI void                                     evas_object_textblock_clear(Evas_Object *obj) EINA_ARG_NONNULL(1);
+
 #include "canvas/evas_textblock.eo.legacy.h"
 
 /**

src/lib/evas/canvas/evas_textblock.eo

@@ -284,7 +284,7 @@ class Evas_Textblock (Evas_Object)
 
          @return nothing. */
 
-         legacy evas_object_textblock_clear_all;
+         legacy null;
       }
       style_user_push {
          /*@