decoder: simplify based on vout_GetPicture() change

Also fixes lot of spurious decoder errors when stopping due to
excessive flush checks.

src/input/decoder.c

@@ -480,18 +480,7 @@ static picture_t *vout_new_buffer( decoder_t *p_dec )
 {
     decoder_owner_sys_t *p_owner = p_dec->p_owner;
 
-    for( ;; )
-    {
-        if( DecoderIsFlushing( p_dec ) || p_dec->b_error )
-            return NULL;
-
-        picture_t *p_picture = vout_GetPicture( p_owner->p_vout );
-        if( p_picture )
-            return p_picture;
-
-        /* FIXME add a vout_WaitPictureAvailable (timedwait) */
-        msleep( VOUT_OUTMEM_SLEEP );
-    }
+    return vout_GetPicture( p_owner->p_vout );
 }
 
 static subpicture_t *spu_new_buffer( decoder_t *p_dec,