mm/rmap: Fix kabi broken in anon_vma

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5JT6V


CVE: NA

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In order to fix CVE-2022-42703, degree in struct anon_vma is splited into
two variables(num_children, num_active_vmas) and this will lead to broken
kabi.

Since struct anon_vma is only used by mm module and referenced by other
struct as pointers. So we can ignore this kabi change warning.

For variable degree in struct anon_vma, previous patch has already
delete this but this will lead to kabi change. Add it back at the same
position with KABI_DEPRECATE.

For variables(num_children, num_active_vmas), add them at the end of
struct anon_vma with KABI_EXTEND.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>