net: handle more error strings in lookupCNAME on Plan 9
On Plan 9, the queryDNS function could return an
error string, which was not handled in lookupCNAME.
This change fixes lookupCNAME by handling the
"resource does not exist; negrcode" error string.
Fixes #67776.
Change-Id: I73f3286b9524a504212ba4303606a245b4962b1f
Reviewed-on: https://go-review.googlesource.com/c/go/+/589715 Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Bypass: David du Colombier <0intro@gmail.com> Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>