What I was more worried about was what happens when sdt.h is included
in
plain C code. Whatever you think of C++ apps that don't play nice with
<limits>, such a complaint is unlikely to impress authors of plain C
apps.
The only header used by <sys/sdt.h> in C is <stdint.h>.
(Frankly I can't tell any more why we even need that, and probably we don't.)