Unroll one-shot decoder struct initialization

Because we are about to add a ready-block channel notifier as a data
member, which cannot be value-initialized in a sensible manner.

pkg/impl/libraptorq/decoder.go

@@ -15,7 +15,11 @@ func (*DecoderFactory) New(commonOTI uint64, schemeSpecificOTI uint32) (
  wrapped := swig.NewBytesDecoder(swig.HostToNet64(commonOTI),
  swig.HostToNet32(schemeSpecificOTI))
  if wrapped.Initialized() {
- decoder = &Decoder{wrapped, commonOTI, schemeSpecificOTI}
+ dec := new(Decoder)
+ dec.wrapped = wrapped
+ dec.commonOTI = commonOTI
+ dec.schemeSpecificOTI = schemeSpecificOTI
+ decoder = dec
  runtime.SetFinalizer(decoder, finalizeDecoder)
  } else {
  swig.DeleteBytesDecoder(wrapped)