Require that FOO_free functions do nothing on NULL.

This is consistent with C's free function and upstream's convention.

Change-Id: I83f6e2f5824e28f69a9916e580dc2d8cb3b94234
Reviewed-on: https://boringssl-review.googlesource.com/4512
Reviewed-by: Adam Langley <agl@google.com>
4 files changed