Move aead_{read,write}_ctx and next_proto_negotiated into ssl->s3.

Both are connection state rather than configuration state. Notably this
cuts down more of SSL_clear that can't just use ssl_free + ssl_new.

Change-Id: I3c05b3ae86d4db8bd75f1cd21656f57fc5b55ca9
Reviewed-on: https://boringssl-review.googlesource.com/6835
Reviewed-by: Adam Langley <alangley@gmail.com>

ssl/s3_lib.c

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index a84227d..6b132ed 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -237,7 +237,10 @@
   OPENSSL_free(ssl->s3->tmp.peer_psk_identity_hint);
   ssl3_free_handshake_buffer(ssl);
   ssl3_free_handshake_hash(ssl);
+  OPENSSL_free(ssl->s3->next_proto_negotiated);
   OPENSSL_free(ssl->s3->alpn_selected);
+  SSL_AEAD_CTX_free(ssl->s3->aead_read_ctx);
+  SSL_AEAD_CTX_free(ssl->s3->aead_write_ctx);
 
   OPENSSL_cleanse(ssl->s3, sizeof *ssl->s3);
   OPENSSL_free(ssl->s3);