Squelch a narrowing warning

Squelch a narrowing warning

Ignore the warning in the way to enable build with -Werror.

To be look at before 2038...

The warning was (clang 64 bits):
./pcap-netfilter-linux.c:346:12: warning: implicit conversion loses
integer precision: 'time_t' (aka 'long') to 'unsigned int'
[-Wshorten-64-to-32]
                seq_id = time(NULL);
                       ~ ^~~~~~~~~~

(cherry picked from commit 16782c7e7811c2bc821c1f58ae948af7bccf81fe)