external/boringssl: Sync to 54c259dec395bd991cce5691723214ffe588e51d.

This includes the following changes:

https://boringssl.googlesource.com/boringssl/+log/8459d0659920ab8c99bd300b8a989d4cda251118..54c259dec395bd991cce5691723214ffe588e51d

Test: BoringSSL CTS Presubmits.
Change-Id: I1868f252e94e424d450ebd8983549d9b13455613
41 files changed