content/local: inline sys.StatATimeAsTime()

The sys.StatATimeAsTime() utility is currently only used in a single place,
but because it's living in the "sys" package, also brings in other dependencies,
such as Microsoft/hcsshim.

This patch inlines the code from sys.StatATimeAsTime(), to remove that dependency.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

content/local/store_unix.go

@@ -1,4 +1,4 @@
-// +build linux solaris darwin freebsd netbsd openbsd
+// +build linux solaris
 
 /*
    Copyright The containerd Authors.
@@ -22,13 +22,11 @@ import (
 	"os"
 	"syscall"
 	"time"
-
-	"github.com/containerd/containerd/sys"
 )
 
 func getATime(fi os.FileInfo) time.Time {
 	if st, ok := fi.Sys().(*syscall.Stat_t); ok {
-		return sys.StatATimeAsTime(st)
+		return time.Unix(int64(st.Atim.Sec), int64(st.Atim.Nsec)) //nolint: unconvert // int64 conversions ensure the line compiles for 32-bit systems as well.
 	}
 
 	return fi.ModTime()