BUILD: tcp_sample: fix build of get_tcp_info() on OpenBSD

The build on OpenBSD is broken since commit 5c83e3a15 ("MINOR: tcp_sample:
clarifying samples support per os, for further expansion."), hence it
only affects 2.7 and 2.6.

It looks like this changed things in such a way that if TCP_INFO is added
but the OS is not added to the list of OS's it will not build.

Extend support for get_tcp_info to OpenBSD.

This must be backported to 2.6.
1 file changed