[clang] Fix #174158: Overly strict warning ‘Unrecognized parameter passing direction’ (PR #174245)

[Roberto Turrado Camblor via cfe-commits]

rturrado wrote:

> As I read the doxygen manual, a space is permitted _instead_ of the comma (so `[in out]` is legal) but not at the ends or as well as the comma. So LLVM is in fact right to reject the two examples you give.

Ah, thanks for the clarification. I misread the doxygen docs. I will add those two new cases to the code and the tests. As for the warning message, we can either enumerate all the cases or provide a more succint text. 



https://github.com/llvm/llvm-project/pull/174245