Disable ClientHello padding for QUIC.

Bug: 327
Change-Id: I415deee8e6b2dc4cd5bdfb5e329d889dd3a5baa7
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42364
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

ssl/t1_lib.cc

diff --git a/ssl/t1_lib.cc b/ssl/t1_lib.cc
index dad0fcf..5032af5 100644
--- a/ssl/t1_lib.cc
+++ b/ssl/t1_lib.cc
@@ -3047,7 +3047,7 @@
     last_was_empty = false;
   }
 
-  if (!SSL_is_dtls(ssl)) {
+  if (!SSL_is_dtls(ssl) && !ssl->quic_method) {
     size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs);
     header_len += 2 + CBB_len(&extensions) + psk_extension_len;
     size_t padding_len = 0;