libpcap: Update PACKAGE_STRING to 1.10.4

Reviewed by: emaste
Fixes: 6f9cba8f8b5e (libpcap: Update to 1.10.3)
Fixes: dd744a896be3 (libpcap: Update to 1.10.4)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D40295