exofs-avoid-vla-in-structures-v2

- use DRY for easier to read stripe updates (ndesaulniers)
- add const to unchanging variable (ndesaulniers)
- update references with message-id URLs
- add Reviewed-by

Link: http://lkml.kernel.org/r/20180418163546.GA45794@beast


Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Boaz Harrosh <ooo@electrozaur.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>