runtime: update netpoll_hurd.go for go1.14beta1 changes

Patch from Svante Signell.

Updates https://gcc.gnu.org/PR93468

Change-Id: I619845f8725bda1d84ed28b7175920bcad262aa2
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/216958
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed