Support atomic directory promotion across platforms

internal/fileops/rename_noreplace_linux.go

@@ -4,6 +4,8 @@ package fileops
 
 import "golang.org/x/sys/unix"
 
+func checkAtomicDirectoryPromotionSupport() error { return nil }
+
 func renameDirectoryNoReplace(src, dst string) error {
 	return unix.Renameat2(unix.AT_FDCWD, src, unix.AT_FDCWD, dst, unix.RENAME_NOREPLACE)
 }