stream_MemoryNew: remove vlc_object_find()

As for the previous commit, this seems more harmful than helpful.

Due to the UTF-16 subtitle hack present in the stream layer, this
commit will break in-memory UTF-16 subtitles character encoding if
UTF-8 autodetection was disabled and unless UTF-8 is the selected
encoding. On the other hand, this commit fixes subtitles encoding
if there is more than one subtitles stream in the whole input.

src/input/stream_memory.c

@@ -76,15 +76,9 @@ stream_t *stream_MemoryNew( vlc_object_t *p_this, uint8_t *p_buffer,
     s->pf_peek    = Peek;
     s->pf_control = Control;
     s->pf_destroy = Delete;
+    s->p_input = NULL;
 
     vlc_object_attach( s, p_this );
-
-    /* Get a weak link to the parent input */
-    /* FIXME: The usage of vlc_object_find has to be removed. */
-    s->p_input = (input_thread_t *)vlc_object_find( p_this, VLC_OBJECT_INPUT, FIND_PARENT );
-    if(s->p_input)
-        vlc_object_release((vlc_object_t*)s->p_input);
-
     return s;
 }