ddns-scripts: Update to 2.7.4

ddns-scripts: Update to 2.7.4

- if local ip cannot be detected or is invalid then do not exit ddns-scripts #2950,
    using multiple url's to detect local ip not jet implemented
- change spdns.de update url and add sydyn.de inside services file #2991
- move transfer- and lookup-program detection to dynamic_dns_functions.sh
    so run once at startup in stead of at every transfer/lookup
- add khost, drill and hostip to verify_host_port() function
- updated tld_names.dat

Signed-off-by: Christian Schoenebeck <redacted>