sw64: add clone3 syscall support

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56XYC



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The implementation of clone3 on sw64 is a bit different from the
generic one.

Signed-off-by: Mao Minkai <maominkai@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>