Add one gigabyte pcap

This patch adds a new test case working on 1 GB pcap. This pcap requires
manual inflating.

* ts/tests/0001_plan.ts. added new test case (disabled by default)
* ts/pcaps/igalia/one-gigabyte.pcap.xz

$ for i in $(seq 1 5); do make test|grep 'tc id 12 AVG ET'; done | sort
tc id 12 AVG ET 2.601421425607e-07
tc id 12 AVG ET 2.6225919589702e-07
tc id 12 AVG ET 2.6275031798649e-07
tc id 12 AVG ET 2.6690385663703e-07
tc id 12 AVG ET 2.7258133084651e-07