BUG/MINOR: halog: exit with error when some output filters are set simultaneosly

BUG/MINOR: halog: exit with error when some output filters are set simultaneosly

Exit with an error if multiple output filters (-ic, -srv, -st, -tc, -u*, etc.)
are used at the same time.

halog is designed to process and display output for only one filter at a time.
Using multiple filters simultaneously can cause a crash because the program is
not designed to manage multiple, separate result sets (e.g., one for
IP counts, another for URLs).

Supporting simultaneous filters would require a redesign to collect entries for
each filter in separate ebtree. This would negatively impact performance and is
not requested for the moment. This patch prevents the crash by checking filter
combinations just after the command line parsing.

This issue was reported in GitHUB #3031.
This should be backported in all stable versions.