conntrack: Remove nat_conn introducing key directionality. #1844

Job	Run time
linux deb no dpdk	7m 58s
linux deb shared dpdk	12m 42s
osx clang --disable-ssl	3m 49s
linux gcc --disable-ssl	3m 10s
linux clang --disable-ssl	3m 4s
linux gcc c99	3m 24s
linux clang c99	5m 8s
linux gcc test	9m 37s
linux clang test asan	20m 53s
linux clang test ubsan	11m 3s
linux gcc test --enable-shared	15m 3s
linux clang test --enable-shared	14m 56s
linux gcc test dpdk	11m 7s
linux clang test dpdk	11m 19s
linux gcc test -ljemalloc	11m 14s
linux clang test -ljemalloc	13m 18s
linux gcc afxdp 5.3	4m 10s
linux clang afxdp 5.3	5m 0s
linux gcc dpdk --enable-shared	6m 18s
linux clang dpdk --enable-shared	4m 15s
linux gcc dpdk-shared	4m 31s
linux clang dpdk-shared	4m 8s
linux gcc dpdk-shared --enable-shared	5m 10s
linux clang dpdk-shared --enable-shared	4m 4s
linux gcc m32 --disable-ssl	3m 16s
	3h 18m 37s

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