Mark PacketCollector QUICHE_EXPORT

quiche::PacketCollector has started being used in quic_connection_test.cc. This requires it to be marked as QUICHE_EXPORT in order to link successfully in component builds of Chromium. The Chromium build treats tests as being a separate component, so the code they use has to be exported.

The macro is a no-op in production builds.

PiperOrigin-RevId: 892609632

quiche/quic/core/quic_buffered_packet_store.h

diff --git a/quiche/quic/core/quic_buffered_packet_store.h b/quiche/quic/core/quic_buffered_packet_store.h
index aed8a42..20e89b5 100644
--- a/quiche/quic/core/quic_buffered_packet_store.h
+++ b/quiche/quic/core/quic_buffered_packet_store.h
@@ -343,7 +343,7 @@
 };
 
 // Collects packets serialized by a QuicPacketCreator.
-class QUICHE_NO_EXPORT PacketCollector
+class QUICHE_EXPORT PacketCollector
     : public QuicPacketCreator::DelegateInterface,
       public QuicStreamFrameDataProducer {
  public: