tests/system-traffic: Ensure no name resolution for tcpdump. #1912

Job	Run time
linux gcc --disable-ssl	3m 22s
osx clang --disable-ssl	3m 41s
linux clang --disable-ssl	3m 2s
linux deb no dpdk	8m 58s
linux gcc c99	3m 47s
linux deb shared dpdk	11m 19s
linux clang c99	3m 2s
linux gcc test	10m 52s
linux clang test asan	21m 20s
linux clang test ubsan	14m 7s
linux gcc test --enable-shared	17m 36s
linux clang test --enable-shared	14m 42s
linux gcc test dpdk	10m 39s
linux clang test dpdk	11m 51s
linux gcc test -ljemalloc	11m 49s
linux clang test -ljemalloc	10m 38s
linux gcc afxdp 5.3	5m 3s
linux clang afxdp 5.3	4m 15s
linux gcc dpdk --enable-shared	4m 58s
linux clang dpdk --enable-shared	4m 30s
linux gcc dpdk-shared	3m 47s
linux clang dpdk-shared	3m 38s
linux gcc dpdk-shared --enable-shared	6m 3s
linux clang dpdk-shared --enable-shared	5m 32s
linux gcc m32 --disable-ssl	4m 2s
	3h 22m 33s

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