controller: Send ARP/ND for stale mac_bindings entries. #3459

Job	Run time
linux rpm fedora	7m 9s
Prepare container	3m 9s
osx clang --disable-ssl	2m 32s
linux gcc --disable-ssl	2m 49s
linux clang --disable-ssl	2m 48s
linux gcc test -300	9m 48s
linux gcc test 301-600	7m 45s
linux gcc test 601- unstable	7m 38s
linux clang test sanitizers -300	13m 11s
linux clang test sanitizers 301-600	10m 46s
linux clang test sanitizers 601- unstable	12m 17s
linux gcc test -ljemalloc -300	10m 33s
linux gcc test -ljemalloc 301-600	8m 2s
linux gcc test -ljemalloc 601- unstable	7m 46s
linux gcc system-test-dpdk dpdk -100	17m 16s
linux gcc system-test-dpdk dpdk 101- unstable	17m 57s
linux gcc system-test-userspace -100	15m 56s
linux gcc system-test-userspace 101- unstable	17m 4s
linux gcc system-test -100	22m 13s
linux gcc system-test 101- unstable	25m 34s
linux clang system-test sanitizers -100	22m 43s
linux clang system-test sanitizers 101- unstable	28m 17s
linux x86 gcc --disable-ssl	2m 48s
	4h 36m 1s

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