Add various options to verify ssl/tls client cert including letting the
application handle the authentication.
diff --git a/grpc.def b/grpc.def
index f81aa1b..17d2ec4 100644
--- a/grpc.def
+++ b/grpc.def
@@ -114,6 +114,7 @@
     grpc_secure_channel_create
     grpc_server_credentials_release
     grpc_ssl_server_credentials_create
+    grpc_ssl_server_credentials_create_ex
     grpc_server_add_secure_http2_port
     grpc_call_set_credentials
     grpc_server_credentials_set_auth_metadata_processor