Fix IPv6-only connectivity
Fix IPv6-only connectivity

Commit a5dd38ec8 ("Assign Address-IP6 field to netmask instead of address")
broke IPv6-only configurations, because we only check for ip_info.addr
and ip_info.addr6 being NULL. We need to allow the connection to continue
when ip_info.netmask6 is non-NULL too.

Reported-by: Dennis Gilmore <7965a665163253a12f43312bf69d07012a113a2a@ausil.us>
Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

mtmiller/openconnect,cernekee/openconnect,lins05/openconnect,nmav/openconnect-mine,lins05/openconnect,mtmiller/openconnect,brandt/openconnect,matlockx/openconnect,mtmiller/openconnect,lins05/openconnect,nmav/openconnect-mine,mtmiller/openconnect,cernekee/openconnect,cernekee/openconnect,matlockx/openconnect,lins05/openconnect,cernekee/openconnect,brandt/openconnect,matlockx/openconnect,nmav/openconnect-mine,matlockx/openconnect,nmav/openconnect-mine,brandt/openconnect,brandt/openconnect