net: acquire thread in resSearch
Change-Id: I042906d8eee8defafbd98f671fd30c2a68281705
GitHub-Last-Rev: 0660c9a989600eeb8652d1228777488d28397731
GitHub-Pull-Request: golang/go#57021
Reviewed-on: https://go-review.googlesource.com/c/go/+/454396
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>