uapi: stddef.h: Fix header guard location

The #endif for the header guard wasn't at the end of the header. This
was harmless since the define that escaped was already testing for its
own redefinition. Regardless, move the #endif to the correct place.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Fixes: c8248fa ("Compiler Attributes: counted_by: Adjust name and identifier expansion")
Link: https://lore.kernel.org/r/b1f5081e-339d-421d-81b2-cbb94e1f6f5f@p183
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

Author: Alexey Dobriyan

include/uapi/linux/stddef.h

@@ -44,8 +44,9 @@
 		struct { } __empty_ ## NAME; \
 		TYPE NAME[]; \
 	}
-#endif
 
 #ifndef __counted_by
 #define __counted_by(m)
 #endif
+
+#endif /* _UAPI_LINUX_STDDEF_H */