Linux added these types to their userspace headers in [6.5], which
causes unit tests to fail like
```
-------- Running tests from test/unit/api/private_helpers_spec.lua
RUN vim_to_object converts true: 17.00 ms ERR
test/unit/helpers.lua:748: test/unit/helpers.lua:732: (string) '
test/unit/helpers.lua:264: ';' expected near '__s128' at line 194'
exit code: 256
stack traceback:
test/unit/helpers.lua:748: in function 'itp_parent'
test/unit/helpers.lua:784: in function <test/unit/helpers.lua:774>
```
Since we don't use these types, they can be ignored to avoid LuaJIT's C
parser choking on them.
[6.5]: 224d80c584
9afbfb4d64