dynarray: Change AV_ to FF_ for AV_DYNARRAY_ADD

The header is not installed and the macro isn't used outside libavutil,
so it is obviously privat to libavutil. Make the name reflect that.

libavutil/dynarray.h

@@ -42,7 +42,7 @@
  *                     array and size are not changed; the statement can end
  *                     with a return or a goto
  */
-#define AV_DYNARRAY_ADD(av_size_max, av_elt_size, av_array, av_size, \
+#define FF_DYNARRAY_ADD(av_size_max, av_elt_size, av_array, av_size, \
                         av_success, av_failure) \
     do { \
         size_t av_size_new = (av_size); \

libavutil/mem.c

@@ -312,7 +312,7 @@ int av_dynarray_add_nofree(void *tab_ptr, int *nb_ptr, void *elem)
     void **tab;
     memcpy(&tab, tab_ptr, sizeof(tab));
 
-    AV_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
+    FF_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
         tab[*nb_ptr] = elem;
         memcpy(tab_ptr, &tab, sizeof(tab));
     }, {
@@ -326,7 +326,7 @@ void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem)
     void **tab;
     memcpy(&tab, tab_ptr, sizeof(tab));
 
-    AV_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
+    FF_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
         tab[*nb_ptr] = elem;
         memcpy(tab_ptr, &tab, sizeof(tab));
     }, {
@@ -340,7 +340,7 @@ void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
 {
     uint8_t *tab_elem_data = NULL;
 
-    AV_DYNARRAY_ADD(INT_MAX, elem_size, *tab_ptr, *nb_ptr, {
+    FF_DYNARRAY_ADD(INT_MAX, elem_size, *tab_ptr, *nb_ptr, {
         tab_elem_data = (uint8_t *)*tab_ptr + (*nb_ptr) * elem_size;
         if (elem_data)
             memcpy(tab_elem_data, elem_data, elem_size);