Account for alloca use when collecting interface addresses (bug 16002)

To reproduce:

	# ip li add name dummy0 type dummy
	# site_id=$(head -c6 /dev/urandom | od -tx2 -An | tr ' ' ':')
	# for ((i = 0; i < 65536; i++)) do
	> ip ad ad $(printf fd80$site_id::%04x $i)/128 dev dummy0
	> done
	# (ulimit -s 900; getent ahosts localhost)
	# ip li de dummy0