There is an OpenBSD bug where the "len" returned by functions like
"getsockname" is too long and makes it so the resulting address contains
zero bytes. While this isn't a problem for C code, where strings are
null terminated anyways, it's a problem for Rust.

This commit fixes this issue by adding a check that truncates the
address length to the first zero when OpenBSD is detected. If there are
no zeroes, it just uses the original length provided by the system.

Signed-off-by: John Nunley <dev@notgull.net>

Signed-off-by: John Nunley <dev@notgull.net>

Signed-off-by: John Nunley <dev@notgull.net>

Signed-off-by: John Nunley <dev@notgull.net>

Signed-off-by: John Nunley <dev@notgull.net>