Add is_quic bit to SSL_SESSION

This bit is used to prevent cross-protocol resumption between QUIC and
TLS-over-TCP.

Bug: 221
Change-Id: I8ab5341f00ae96c0a5f7ac3999f61edc7cbeca1c
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/40444
Commit-Queue: Nick Harper <nharper@chromium.org>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/internal.h b/ssl/internal.h
index ac3a844..04bf7a4 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -3548,6 +3548,9 @@
   // is_server is whether this session was created by a server.
   bool is_server : 1;
 
+  // is_quic indicates whether this session was created using QUIC.
+  bool is_quic : 1;
+
  private:
   ~ssl_session_st();
   friend void SSL_SESSION_free(SSL_SESSION *);