legacysupport implementation of fdopendir closes fd, and this breaks some software

[kencu (Ken)]

After fdopendir was added to legacysupport, it was noted that there was a leak in the function.

So an interested user added a new bit of code to our fdopendir function to close the fd.

​https://github.com/macports/macports-legacy-support/commit/3c9d3c2fc4efb9d1e58e9fb9d44899463391a276

This seemed to meet the implementation spec at the time:

"After a successful call to fdopendir(), fd is used internally by the implementation, and should not otherwise be used by the application."

but it turns out that some software still uses "fd" after the call to fdopendir. So this software is broken by the fdopendir implementation in macports.

see:

​https://github.com/macports/macports-ports/pull/19047

This does seem to be in the POSIX spec:

​https://pubs.opengroup.org/onlinepubs/9699919799/functions/fdopendir.html

"Upon successful return from fdopendir(), the file descriptor is under the control of the system, and if any attempt is made to close the file descriptor, or to modify the state of the associated description, other than by means of closedir(), readdir(), readdir_r(), rewinddir(), or seekdir(), the behavior is undefined. Upon calling closedir() the file descriptor shall be closed."

So fdopendir may need to be changed to close the fd later, when closedir is called.