If an invalid rdclass was passed to getrrsetbyname() then
this would execute a free on an uninitialised pointer.
OpenSSH only ever calls this with a fixed and valid rdclass.
Reported by Joshua Rogers
openbsd-compat/getrrsetbyname-ldns.c openbsd-compat/getrrsetbyname.c]
bz 1320: Add optional support for LDNS, a BSD licensed DNS resolver library
which supports DNSSEC. Patch from Simon Vallet (svallet at genoscope cns fr)
with some rework from myself and djm. ok djm.