Set LIBPROTOBUF_EXPORT on GzipOutputStream::Options
Set LIBPROTOBUF_EXPORT on GzipOutputStream::Options

This fixes issue #2610.

This was originally fixed in a101fa52895fc2ad83d8b5d610243531b1608a08 , but got
reverted by d36c0c538a545fac5d9db6ba65c525246d4efa95

google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf