Closes #22258: Fix the the internal function set_inheritable() on Illumos.
This platform exposes the function ioctl(FIOCLEX), but calling it fails with
errno is ENOTTY: "Inappropriate ioctl for device". set_inheritable() now falls
back to the slower fcntl() (F_GETFD and then F_SETFD).

--HG--
branch : 3.4