The AllowedSender directive misbehaved if network was down during startup

The passing of the AI_ADDRCONFIG flag to getaddrinfo() caused IP
prefixes to be interpreted as hostname wildcards if network was down
during rsyslog's startup.
Merge pull request #148 from rsyslog/v7-stable-th-allowedsender

The AllowedSender directive misbehaved if network down during startup