kselftest/vm: fix tests build with old libc

kselftest/vm: fix tests build with old libc

BugLink: https://bugs.launchpad.net/bugs/1969678
[ Upstream commit b773827e361952b3f53ac6fa4c4e39ccd632102e ]

The error message when I build vm tests on debian10 (GLIBC 2.28):

    userfaultfd.c: In function `userfaultfd_pagemap_test':
    userfaultfd.c:1393:37: error: `MADV_PAGEOUT' undeclared (first use
    in this function); did you mean `MADV_RANDOM'?
      if (madvise(area_dst, test_pgsize, MADV_PAGEOUT))
                                         ^~~~~~~~~~~~
                                         MADV_RANDOM

This patch includes these newer definitions from UAPI linux/mman.h, is
useful to fix tests build on systems without these definitions in glibc
sys/mman.h.

Link: https://lkml.kernel.org/r/20220227055330.43087-2-zhouchengming@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>