I've applied the following patches to the 2.18 branch. I initially pushed them
for the ibm derivative, but they should go here too.

I ran into a conflict applying BZ #19791.  It turns out it was caused by another
bug fixed upstream, so I applied it as well.

1e18675 resolv: Always set *resplen2 out parameter in send_dg [BZ #19791]
69242db Fix invalid file descriptor reuse while sending DNS query (BZ #15946)
97eff76 CVE-2015-7547: getaddrinfo() stack-based buffer overflow (Bug 18665).