Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21905)
=back
+Third parties implementing custom BIOs supporting the BIO_sendmmsg() or
+BIO_recvmmsg() methods should note that it is a required part of the API
+contract that an error is always raised when either of these functions return 0.
+
BIO_dgram_set_local_addr_enable() returns 1 if local address support was
successfully enabled or disabled and 0 otherwise.