imdecode function
Implementation
VARP imdecode(Uint8List data, {int flags = IMREAD_COLOR}) {
final pData = calloc<ffi.Uint8>(data.length)..asTypedList(data.length).setAll(0, data);
final pOut = c.mnn_cv_imdecode(pData, data.length, flags);
final rval = VARP.fromPointer(pOut);
calloc.free(pData);
return rval;
}