It was removed in the fork but it turned out to need it.

Change-Id: I21030c8d5befecb63f2c40a59963bec1da1d96fb
Reviewed-on: https://boringssl-review.googlesource.com/1081
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)