CXX-1414 Fix gcc 4.8 error
CXX-1414 Fix gcc 4.8 error

Using a mongoc_change_stream_t reference in a braced initializer yields "invalid initialization of
non-const reference."

acmorrow/mongo-cxx-driver,acmorrow/mongo-cxx-driver,mongodb/mongo-cxx-driver,acmorrow/mongo-cxx-driver,mongodb/mongo-cxx-driver,mongodb/mongo-cxx-driver,acmorrow/mongo-cxx-driver,mongodb/mongo-cxx-driver