Overly strict warning ‘Unrecognized parameter passing direction’

The tag `@param[inout]` in a doxygen comment triggers the clang warning

`Unrecognized parameter passing direction, valid directions are ‘[in]’, ‘[out]’ and ‘[in,out]’`

But the [doxygen documentation](https://www.doxygen.nl/manual/commands.html#cmdparam) explicitly states that

> For the bidirecional values, directions “in” and “out” can be specified in any order, and they can either be written altogether, or separated with a comma (,) or a space. That means that for example values “[outin]” or “[in out]” are also valid.

If this were in my own code, I’d just shrug and insert the comma. But it’s in a third party header, and I’m not inclined to make a bug report to that header’s owner when it is correct according to the docs. So I'm reporting it here instead.