Pass explicit hs parameters to kExtensions callbacks.

This takes care of many of the explicit ssl->s3->hs accesses.

Change-Id: I380fae959f3a7021d6de9d19a4ca451b9a0aefe5
Reviewed-on: https://boringssl-review.googlesource.com/12317
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/tls13_server.c b/ssl/tls13_server.c
index eaeab06..27a92b9 100644
--- a/ssl/tls13_server.c
+++ b/ssl/tls13_server.c
@@ -119,7 +119,7 @@
   }
 
   /* TLS extensions. */
-  if (!ssl_parse_clienthello_tlsext(ssl, &client_hello)) {
+  if (!ssl_parse_clienthello_tlsext(hs, &client_hello)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
     return ssl_hs_error;
   }
@@ -410,7 +410,7 @@
   CBB cbb, body;
   if (!ssl->method->init_message(ssl, &cbb, &body,
                                  SSL3_MT_ENCRYPTED_EXTENSIONS) ||
-      !ssl_add_serverhello_tlsext(ssl, &body) ||
+      !ssl_add_serverhello_tlsext(hs, &body) ||
       !ssl_complete_message(ssl, &cbb)) {
     CBB_cleanup(&cbb);
     return ssl_hs_error;