1. Remove unused fields, such as AnfNode::interpreted_node_, CNode::inputs_value_;
2. Reduce seen_ size from 64 bits to 32 bits;
3. Use bitset for boolean flags;
4. Use pointer for user data;
5. Make some cold fields as user data, such as AnfNode::kernel_info_.

Object size decreased:
AnfNode: 232 -> 144
ValueNode: 264 -> 176
Parameter: 384 -> 272
CNode: 576 -> 400

Signed-off-by: zhoufeng <zhoufeng54@huawei.com>