CBB_init_fixed callers no longer need to check the return value, or handle any cleanup. The hpke.c instance was even already (incorrectly at the time) assuming this. Change-Id: I2f4cb124454fc7ba7ff6d2075d99f537a58c6c6b Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/54647 Reviewed-by: Bob Beck <bbe@google.com> Commit-Queue: David Benjamin <davidben@google.com>