Fix load balanced hairpin traffic for fragmented packets. #3255

Job	Run time
linux rpm fedora	6m 37s
dpdk gcc	5s
osx clang --disable-ssl	2m 0s
Prepare container	2m 7s
linux gcc --disable-ssl	2m 13s
linux clang --disable-ssl	2m 17s
linux gcc test -300	8m 53s
linux gcc test 301-600	5m 40s
linux gcc test 601- unstable	6m 1s
linux clang test sanitizers -300	11m 50s
linux clang test sanitizers 301-600	7m 55s
linux clang test sanitizers 601- unstable	9m 50s
linux gcc test -ljemalloc -300	9m 13s
linux gcc test -ljemalloc 301-600	5m 52s
linux gcc test -ljemalloc 601- unstable	6m 3s
linux gcc system-test-dpdk dpdk -100	16m 0s
linux gcc system-test-dpdk dpdk 101- unstable	11m 12s
linux gcc system-test-userspace -100	14m 53s
linux gcc system-test-userspace 101- unstable	10m 29s
linux gcc system-test -100	17m 36s
linux gcc system-test 101- unstable	13m 54s
linux clang system-test sanitizers -100	19m 40s
linux clang system-test sanitizers 101- unstable	15m 41s
linux x86 gcc --disable-ssl	2m 9s
	3h 28m 10s

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