Fix a failure to NULL a pointer freed on error.

Reported by the LibreSSL project as a follow on to CVE-2015-0209

(Imported from upstream's 5e5d53d341fd9a9b9cc0a58eb3690832ca7a511f.)

Change-Id: Ic2e5dc5c96e316c55f76bedc6ea55b416be3287a
Reviewed-on: https://boringssl-review.googlesource.com/4049
Reviewed-by: Adam Langley <agl@google.com>
2 files changed