Remove QUICHE_EXPORT in quic_simple_client_session.cc to fix merge.

PiperOrigin-RevId: 500588438

quiche/quic/tools/quic_simple_client_session.cc

diff --git a/quiche/quic/tools/quic_simple_client_session.cc b/quiche/quic/tools/quic_simple_client_session.cc
index 9de95d8..d6085d2 100644
--- a/quiche/quic/tools/quic_simple_client_session.cc
+++ b/quiche/quic/tools/quic_simple_client_session.cc
@@ -12,7 +12,7 @@
 
 namespace {
 
-class QUICHE_EXPORT ServerPreferredAddressResultDelegateWithWriter
+class ServerPreferredAddressResultDelegateWithWriter
     : public QuicPathValidator::ResultDelegate {
  public:
   explicit ServerPreferredAddressResultDelegateWithWriter(