Allow NULL inputs in SSL_SESSION_get_time.

Some code relies on OpenSSL's behavior where it allowed for NULL. But this time
add a comment so people don't think this is the convention for new functions.

BUG=538292

Change-Id: I66566e0e24566fafe17e05369276248be3b05591
Reviewed-on: https://boringssl-review.googlesource.com/6070
Reviewed-by: Adam Langley <agl@google.com>
1 file changed