Add |SSL_CTX_set0_buffer_pool|.

This currently only works for certificates parsed from the network, but
if making several connections that share certificates, some KB of memory
might be saved.

BUG=chromium:671420

Change-Id: I1c7a71d84e1976138641f71830aafff87f795f9d
Reviewed-on: https://boringssl-review.googlesource.com/12706
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/internal.h b/ssl/internal.h
index cd5db9e..3640b65 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -762,7 +762,8 @@
  * |out_leaf_sha256|. */
 STACK_OF(CRYPTO_BUFFER) *ssl_parse_cert_chain(uint8_t *out_alert,
                                               uint8_t *out_leaf_sha256,
-                                              CBS *cbs);
+                                              CBS *cbs,
+                                              CRYPTO_BUFFER_POOL *pool);
 
 /* ssl_add_cert_to_cbb adds |x509| to |cbb|. It returns one on success and zero
  * on error. */