[gcc(refs/users/guojiufu/heads/guojiufu-branch)] internal/syscall/unix: add hurd build tag

[Jiu Fu Guo]

https://gcc.gnu.org/g:027a3f1c38727a1ea0969088b0680b2f6bb1e977

commit 027a3f1c38727a1ea0969088b0680b2f6bb1e977
Author: Ian Lance Taylor <iant@golang.org>
Date:   Mon Feb 24 06:38:11 2020 -0800

    internal/syscall/unix: add hurd build tag
    
    Patch from Svante Signell.
    
    Fixes GCC PR go/93900
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/220589

Diff:
---
 gcc/go/gofrontend/MERGE                       | 2 +-
 libgo/go/internal/syscall/unix/nonblocking.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index ce10ee1d8d4..47fbeaeda61 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-d5d00d310ec33aeb18f33f807956ec0c4eeea6bb
+4e6402f3153fad368830ff3fe57c6302179de806
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/go/internal/syscall/unix/nonblocking.go b/libgo/go/internal/syscall/unix/nonblocking.go
index 9b39bb24087..1734cdc5124 100644
--- a/libgo/go/internal/syscall/unix/nonblocking.go
+++ b/libgo/go/internal/syscall/unix/nonblocking.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd hurd linux netbsd openbsd
 
 package unix