When system headers expose a strict "open" prototype with
3 args, arrange to expose a C++ overload with only two.
2021-01-10 Olivier Hainque <hainque@adacore.com>
* inclhack.def (vxworks_math_h_fp_c99): New hack.
* tests/base/fcntl.h: Update.
* fixincl.x: Regenerate.