Release some temporaries outside of ClientHello callbacks.

Also add ECH GREASE state into the mix. Clearing this isn't critical,
especially now that we have an SSL_HANDSHAKE structure, but it's easy
enough.

Bug: 275
Change-Id: If1aa8d5c0c8fdb5af710852778ce452c507a2524
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47985
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/tls13_client.cc b/ssl/tls13_client.cc
index 37ca4b2..c7f45f6 100644
--- a/ssl/tls13_client.cc
+++ b/ssl/tls13_client.cc
@@ -260,6 +260,7 @@
     return ssl_hs_error;
   }
 
+  ssl_done_writing_client_hello(hs);
   hs->tls13_state = state_read_server_hello;
   return ssl_hs_flush;
 }