Fix an unchecked allocation.

Also mark other allocation failures with our unlikely macro.

src/opusfile.c

@@ -1549,7 +1549,7 @@ static int op_open_seekable2(OggOpusFile *_of){
   start_op_count=_of->op_count;
   /*This is a bit too large to put on the stack unconditionally.*/
   op_start=(ogg_packet *)_ogg_malloc(sizeof(*op_start)*start_op_count);
-  if(op_start==NULL)return OP_EFAULT;
+  if(OP_UNLIKELY(op_start==NULL))return OP_EFAULT;
   *&oy_start=_of->oy;
   *&os_start=_of->os;
   prev_page_offset=_of->prev_page_offset;
@@ -1669,6 +1669,7 @@ static int op_open1(OggOpusFile *_of,
   /*Don't seek yet.
     Set up a 'single' (current) logical bitstream entry for partial open.*/
   _of->links=(OggOpusLink *)_ogg_malloc(sizeof(*_of->links));
+  if(OP_UNLIKELY(_of->links==NULL))return OP_EFAULT;
   /*The serialno gets filled in later by op_fetch_headers().*/
   ogg_stream_init(&_of->os,-1);
   pog=NULL;
@@ -2902,7 +2903,7 @@ static int op_ensure_buffer(OggOpusFile *_of,int _duration,int _nchannels){
   if(capacity>_of->od_buffer_capacity){
     op_sample *new_buffer;
     new_buffer=(op_sample *)_ogg_realloc(_of->od_buffer,capacity);
-    if(new_buffer==NULL)return OP_EFAULT;
+    if(OP_UNLIKELY(new_buffer==NULL))return OP_EFAULT;
     _of->od_buffer=new_buffer;
     _of->od_buffer_capacity=capacity;
   }