[test-object] Hopefully last ubsan fix

API change:
- hb_face_is_immutable() now takes `hb_face_t *` instead of previous
  `const hb_face_t *`.  This should not pose any problem for any
  clients in our belief.

src/hb-face.cc

@@ -672,7 +672,7 @@ hb_face_make_immutable (hb_face_t *face)
  * Since: 0.9.2
  **/
 hb_bool_t
-hb_face_is_immutable (const hb_face_t *face)
+hb_face_is_immutable (hb_face_t *face)
 {
   return hb_object_is_immutable (face);
 }

src/hb-face.h

@@ -131,7 +131,7 @@ HB_EXTERN void
 hb_face_make_immutable (hb_face_t *face);
 
 HB_EXTERN hb_bool_t
-hb_face_is_immutable (const hb_face_t *face);
+hb_face_is_immutable (hb_face_t *face);
 
 
 HB_EXTERN hb_blob_t *

test/api/test-object.c

@@ -29,52 +29,52 @@
 /* Unit tests for hb-object-private.h */
 
 
-static void *
+static hb_blob_t *
 create_blob (void)
 {
   static char data[] = "test data";
   return hb_blob_create (data, sizeof (data), HB_MEMORY_MODE_READONLY, NULL, NULL);
 }
-static void *
+static hb_blob_t *
 create_blob_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_buffer_t *
 create_buffer (void)
 {
   return hb_buffer_create ();
 }
-static void *
+static hb_buffer_t *
 create_buffer_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_map_t *
 create_map (void)
 {
   return hb_map_create ();
 }
-static void *
+static hb_map_t *
 create_map_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_set_t *
 create_set (void)
 {
   return hb_set_create ();
 }
-static void *
+static hb_set_t *
 create_set_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_face_t *
 create_face (void)
 {
   hb_blob_t *blob = (hb_blob_t *) create_blob ();
@@ -82,13 +82,13 @@ create_face (void)
   hb_blob_destroy (blob);
   return face;
 }
-static void *
+static hb_face_t *
 create_face_from_inert (void)
 {
   return hb_face_create (hb_blob_get_empty (), 0);
 }
 
-static void *
+static hb_font_t *
 create_font (void)
 {
   hb_face_t *face = (hb_face_t *) create_face ();
@@ -96,24 +96,24 @@ create_font (void)
   hb_face_destroy (face);
   return font;
 }
-static void *
+static hb_font_t *
 create_font_from_inert (void)
 {
   return hb_font_create (hb_face_get_empty ());
 }
 
-static void *
+static hb_font_funcs_t *
 create_font_funcs (void)
 {
   return hb_font_funcs_create ();
 }
-static void *
+static hb_font_funcs_t *
 create_font_funcs_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_shape_plan_t *
 create_shape_plan (void)
 {
   hb_segment_properties_t props = HB_SEGMENT_PROPERTIES_DEFAULT;
@@ -123,18 +123,18 @@ create_shape_plan (void)
   hb_face_destroy (face);
   return shape_plan;
 }
-static void *
+static hb_shape_plan_t *
 create_shape_plan_from_inert (void)
 {
   return NULL;
 }
 
-static void *
+static hb_unicode_funcs_t *
 create_unicode_funcs (void)
 {
   return hb_unicode_funcs_create (NULL);
 }
-static void *
+static hb_unicode_funcs_t *
 create_unicode_funcs_from_inert (void)
 {
   return hb_unicode_funcs_create (hb_unicode_funcs_get_empty ());
@@ -179,11 +179,11 @@ static void \
 test_object_##name (void) \
 { \
   typedef hb_##name##_t type_t; \
-  typedef void     *(*create_func_t)         (void); \
+  typedef type_t   *(*create_func_t)         (void); \
   typedef type_t   *(*reference_func_t)      (type_t *obj); \
   typedef void      (*destroy_func_t)        (type_t *obj); \
   typedef hb_bool_t (*set_user_data_func_t)  (type_t *obj, hb_user_data_key_t *key, void *data, hb_destroy_func_t destroy, hb_bool_t replace); \
-  typedef void *    (*get_user_data_func_t)  (type_t *obj, hb_user_data_key_t *key); \
+  typedef void *    (*get_user_data_func_t)  (const type_t *obj, hb_user_data_key_t *key); \
   typedef void      (*make_immutable_func_t) (type_t *obj); \
   typedef hb_bool_t (*is_immutable_func_t)   (type_t *obj); \
  \
@@ -199,15 +199,15 @@ test_object_##name (void) \
     is_immutable_func_t    is_immutable; \
     const char            *name; \
   } o[1] = {{\
-    (create_func_t)         create_##name, \
-    (create_func_t)         create_##name##_from_inert, \
-    (create_func_t)         hb_##name##_get_empty, \
-    (reference_func_t)      hb_##name##_reference, \
-    (destroy_func_t)        hb_##name##_destroy, \
-    (set_user_data_func_t)  hb_##name##_set_user_data, \
-    (get_user_data_func_t)  hb_##name##_get_user_data, \
-    (make_immutable_func_t) _hb_object_make_immutable, \
-    (is_immutable_func_t)   _hb_object_is_immutable, \
+    create_##name, \
+    create_##name##_from_inert, \
+    hb_##name##_get_empty, \
+    hb_##name##_reference, \
+    hb_##name##_destroy, \
+    hb_##name##_set_user_data, \
+    hb_##name##_get_user_data, \
+    _hb_object_make_immutable, \
+    _hb_object_is_immutable, \
     #name, \
   }}; \
  \