Merge pull request #6579 from zhsj/fix-gccgo

Fix build with gccgo

mount/subprocess_unsafe_gc.go

@@ -1,3 +1,6 @@
+//go:build linux && gc
+// +build linux,gc
+
 /*
    Copyright The containerd Authors.
 

mount/subprocess_unsafe_gccgo.go

@@ -0,0 +1,33 @@
+//go:build linux && gccgo
+// +build linux,gccgo
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mount
+
+import (
+	_ "unsafe" // required for go:linkname.
+)
+
+//go:linkname beforeFork syscall.runtime__BeforeFork
+func beforeFork()
+
+//go:linkname afterFork syscall.runtime__AfterFork
+func afterFork()
+
+//go:linkname afterForkInChild syscall.runtime__AfterForkInChild
+func afterForkInChild()