libgo: Hurd portability patches By Svante Signell. Fixes https://gcc.gnu.org/PR93020 Change-Id: I8b52d4f7dd4cb248a2c27bdd19ee3b33666373b3 Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/212409 Reviewed-by: Ian Lance Taylor <iant@golang.org>