[Script] Add pointer arthematic

[yaoyaoding]

def test_const_pointer():
    from hidet.lang import attrs, void_p, printf, int32

    with hidet.script_module() as script_module:

        @hidet.script
        def func():
            attrs.func_kind = 'host_kernel'

            v = int32(0)  # int32 v = 0;
            p_int32 = ~v  # int32* p_int32 = &v;
            p_void = void_p(p_int32)  # void* p_void = (void*)p_int32;
            printf("%p\n", p_void)

            p_void_0 = void_p(0)  # void* p_void_0 = (void*)0;
            printf("%p\n", p_void_0)

            p_void_1 = p_void_0 + 1
            p_void_2 = p_void_1 - 1
            printf("%p\n", p_void_1)
            printf("%p\n", p_void_2)
            printf("%d\n", p_void_1 == p_void_2)
            printf("%d\n", p_void_1 == p_void_2 + 1)
            printf("%p\n", p_int32 + 1)

    func = script_module.build()
    func()

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(nil)
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