aufs: minor, for userspace, don't use typeof

This is detected by the commit in v5.3-rc1,
	d6fc9fcbaa65 2019-07-08 kbuild: compile-test exported headers to
		ensure they are self-contained
But the issue is not for v5.3-rc1 only I am afraid.  So this commit is
brought to aufs4.14 which is my current development base.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit d38615f7fef1c65e30e3cc418daa9e19c93ed98f)

include/uapi/linux/aufs_type.h

@@ -241,7 +241,11 @@ enum {
 
 /* borrowed from linux/include/linux/kernel.h */
 #ifndef ALIGN
+#ifdef _GNU_SOURCE
 #define ALIGN(x, a)		__ALIGN_MASK(x, (typeof(x))(a)-1)
+#else
+#define ALIGN(x, a)		(((x) + (a) - 1) & ~((a) - 1))
+#endif
 #define __ALIGN_MASK(x, mask)	(((x)+(mask))&~(mask))
 #endif