kselftest/vm: fix tests build with old libc

stable inclusion
from stable-v5.10.107
commit 8fdaab341bad8a8449fcdca349e5081e6f62db09
bugzilla: https://gitee.com/openeuler/kernel/issues/I574A2

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8fdaab341bad8a8449fcdca349e5081e6f62db09

--------------------------------

[ Upstream commit b773827e ]

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.comSigned-off-by: NChengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: NShuah Khan <skhan@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

tools/testing/selftests/vm/userfaultfd.c

@@ -46,6 +46,7 @@
 #include <signal.h>
 #include <poll.h>
 #include <string.h>
+#include <linux/mman.h>
 #include <sys/mman.h>
 #include <sys/syscall.h>
 #include <sys/ioctl.h>