external/boringssl: Sync to 68f37b7a3f451aa1ca8c93669c024d01f6270ae8.

This includes the following changes:

https://boringssl.googlesource.com/boringssl/+log/3ef7697ed30f28367395a5aafb57a12a19906d96..68f37b7a3f451aa1ca8c93669c024d01f6270ae8

Test: cts-tradefed run cts -m CtsLibcoreOkHttpTestCases -a arm64-v8a
Test: cts-tradefed run cts -m CtsLibcoreTestCases -a arm64-v8a

Change-Id: I296d05afab7470335cdda2442414a858df591f6c
diff --git a/src/include/openssl/tls1.h b/src/include/openssl/tls1.h
index 35d3145..dfaf78a 100644
--- a/src/include/openssl/tls1.h
+++ b/src/include/openssl/tls1.h
@@ -205,13 +205,14 @@
 /* ExtensionType value from RFC4507 */
 #define TLSEXT_TYPE_session_ticket 35
 
-/* ExtensionType values from draft-ietf-tls-tls13-16 */
+/* ExtensionType values from draft-ietf-tls-tls13-18 */
 #define TLSEXT_TYPE_supported_groups 10
 #define TLSEXT_TYPE_key_share 40
 #define TLSEXT_TYPE_pre_shared_key 41
 #define TLSEXT_TYPE_early_data 42
 #define TLSEXT_TYPE_supported_versions 43
 #define TLSEXT_TYPE_cookie 44
+#define TLSEXT_TYPE_psk_key_exchange_modes 45
 
 /* ExtensionType value from RFC5746 */
 #define TLSEXT_TYPE_renegotiate 0xff01