fix SETFL

[CvvT]

 F_SETFL
              Set the file status flags to the value specified by arg.
              File access mode (O_RDONLY, O_WRONLY, O_RDWR) and file
              creation flags (i.e., O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC)
              in arg are ignored.  On Linux, this operation can change
              only the O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME, and
              O_NONBLOCK flags.  It is not possible to change the O_DSYNC
              and O_SYNC flags; see BUGS, below.

The previous implementation didn't ignore File access mode. This PR fixes that. With this change, we should be able to run curl.

[github-actions]

🤖 SemverChecks 🤖 No breaking API changes detected

Note: this does not mean API is unchanged, or even that there are no breaking changes; simply, none of the detections triggered.