Fix gfe_quic_fuzzer for IETF quic.

PiperOrigin-RevId: 378195995

quic/core/tls_server_handshaker.h

diff --git a/quic/core/tls_server_handshaker.h b/quic/core/tls_server_handshaker.h
index 3675ee1..2715415 100644
--- a/quic/core/tls_server_handshaker.h
+++ b/quic/core/tls_server_handshaker.h
@@ -176,6 +176,10 @@
       std::string signature,
       std::unique_ptr<ProofSource::Details> details) override;
 
+  void set_encryption_established(bool encryption_established) {
+    encryption_established_ = encryption_established;
+  }
+
   bool WillNotCallComputeSignature() const override;
 
   const bool close_proof_source_handle_promptly_ =