This reverts commit 0c1aef58.

The close_range(2) system call is too recent and not recognized by the
host system on CircleCI, so the fedora-latest container detects it but
is denied execution (EPERM) from the host's libseccomp.

Also, on platforms with neither close_range(2) nor closefrom(2) we ended
up not including <dirent.h> and failing virtually everywhere in our CI.

The ifdef dance could have looked like this:

    #ifdef HAVE_LINUX_CLOSE_RANGE_H
    #  include <linux/close_range.h>
    #elif HAVE_CLOSEFROM
    #else
    #  include <dirent.h>
    #endif

Note the extra #else missing from the original patch.

This is reverted for now because we need to check that close_range(2)
works at configure time to circumvent the host mismatch problem.