ic: Fix vxlan encap mode. #4781

Job	Run time
linux rpm fedora	7m 7s
Prepare container	3m 26s
osx clang --disable-ssl	1m 58s
linux gcc --disable-ssl	2m 45s
linux clang --disable-ssl	2m 42s
linux gcc test -300	9m 34s
linux gcc test 301-600	6m 41s
linux gcc test 601- unstable	7m 4s
linux clang test sanitizers -300	13m 23s
linux clang test sanitizers 301-600	9m 19s
linux clang test sanitizers 601- unstable	11m 59s
linux gcc test -ljemalloc -300	10m 10s
linux gcc test -ljemalloc 301-600	6m 55s
linux gcc test -ljemalloc 601- unstable	7m 37s
linux gcc system-test-dpdk dpdk -100	17m 4s
linux gcc system-test-dpdk dpdk 101- unstable	14m 46s
linux gcc system-test-userspace -100	16m 0s
linux gcc system-test-userspace 101- unstable	13m 56s
linux gcc system-test -100	18m 17s
linux gcc system-test 101- unstable	18m 3s
linux clang system-test sanitizers -100	20m 19s
linux clang system-test sanitizers 101- unstable	20m 4s
linux x86 gcc --disable-ssl	2m 36s
	4h 1m 45s

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