tests/system-traffic: Ensure no name resolution for tcpdump. #2351

Job	Run time
osx clang --disable-ssl	4m 12s
linux deb no dpdk	6m 52s
linux gcc --disable-ssl	3m 16s
linux deb shared dpdk	15m 55s
linux clang --disable-ssl	4m 7s
linux gcc c99	3m 53s
linux clang c99	3m 12s
linux gcc test	10m 31s
linux clang test asan	18m 15s
linux clang test ubsan	14m 11s
linux gcc test --enable-shared	17m 10s
linux clang test --enable-shared	13m 51s
linux gcc test dpdk	12m 49s
linux clang test dpdk	13m 7s
linux gcc test -ljemalloc	12m 26s
linux clang test -ljemalloc	12m 32s
linux gcc afxdp 5.3	4m 8s
linux clang afxdp 5.3	3m 56s
linux gcc dpdk --enable-shared	5m 3s
linux clang dpdk --enable-shared	4m 57s
linux gcc dpdk-shared	4m 29s
linux clang dpdk-shared	4m 32s
linux gcc dpdk-shared --enable-shared	6m 32s
linux clang dpdk-shared --enable-shared	4m 4s
linux gcc m32 --disable-ssl	4m 4s
	3h 28m 4s

Provide feedback