unix: Convert from AVERROR to errno range before comparing error codes

Signed-off-by: Martin Storsjö <martin@martin.st>
tcp: Use a different log message and level if there's more addresses to try

This lowers the level of warnings printed if trying to connect
to a host name that provides both v6 and v4 addresses but the
service only is available on the v4 address (often occurring for
'localhost', with servers that aren't v6-aware).

Signed-off-by: Martin Storsjö <martin@martin.st>
avformat/dv: K&R formatting cosmetics