syscallcompat: add Darwin version of unix2syscall

The "Atim" field is called "Atimespec" on Darwin,
same for Mtim and Ctim.

internal/syscallcompat/unix2syscall_darwin.go

@@ -0,0 +1,26 @@
+package syscallcompat
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// Unix2syscall converts a unix.Stat_t struct to a syscall.Stat_t struct.
+func Unix2syscall(u unix.Stat_t) syscall.Stat_t {
+	return syscall.Stat_t{
+		Dev:       u.Dev,
+		Ino:       u.Ino,
+		Nlink:     u.Nlink,
+		Mode:      u.Mode,
+		Uid:       u.Uid,
+		Gid:       u.Gid,
+		Rdev:      u.Rdev,
+		Size:      u.Size,
+		Blksize:   u.Blksize,
+		Blocks:    u.Blocks,
+		Atimespec: syscall.Timespec(u.Atimespec),
+		Mtimespec: syscall.Timespec(u.Mtimespec),
+		Ctimespec: syscall.Timespec(u.Ctimespec),
+	}
+}