audit: Avoid build failures on systems without renameat

renameat has been deprecated in favor of renameat2 for new ports.  This
allows the audit tests to build on RISC-V.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

include/asm-generic/audit_dir_write.h

@@ -27,7 +27,9 @@ __NR_mknod,
 __NR_mkdirat,
 __NR_mknodat,
 __NR_unlinkat,
+#ifdef __NR_renameat
 __NR_renameat,
+#endif
 __NR_linkat,
 __NR_symlinkat,
 #endif