Update Referrer.pm to set host to securehost if host is undefined

[photomedia]

Recent version of EPrints has introdiced a simplified means for configuration EPrints for HTTPS only:

https://wiki.eprints.org/w/Simplified_HTTPS_Configuration

This means that there could be issue with setting $self->{host} = $self->{session}->config( "host" ); if HTTPS only configuration is defined in the archive's cfg/cfg.d/10_core.pl. In that case, {host} is undefined, and only {securehost] is defined.

irstats2/lib/plugins/EPrints/Plugin/Stats/Processor/Access/Referrer.pm

Line 24 in 74ce563

$self->{host} = $self->{session}->config( "host" );

Could this line be changed so that 'securehost' variable is used instead of 'host' when 'host' is undefined?