geoip: Fix sign compare warnings

array_size() returns size_t, thus make iterator variables comparing
against it  size_t too to avoid a warning regarding comparison of
signed/unsigned.

Also cast some ssize_t variables passed to min() for the same reason.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
flowtop: Mark unused parameters with __maybe_unused

In order to avoid compiler warnings when compiling with
-W/-Wunused-parameter, mark unused function parameters with
__maybe_unused.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>