Editing with vim clears Windows 10 file system archive bit.

[Christian Franke]

Steve Ward via Cygwin wrote:
> Description of problem:
> While using vim 8.2 on cygwin 3.3 (x86_64) on Windows 10,
> when editing an existing file with vim and saving it, the Window’s
> file system archive bit is always left cleared (not modified state).
> This happens, whether the archive bit was set (is modified) or
> clear (not modified) initially.

The problem also occurs with 'cp' command:

$ touch file1

$ /bin/cp file1 file2

$ /bin/cp --preserve=mode file1 file3

$ lsattr file?
---a-------- file1
---a-------- file2
------------ file3

Some Cygwin functions apparently clear the archive attribute 
unexpectedly, for example:

int fd = open(filename, O_CREAT|O_TRUNC|O_WRONLY, 0644);
write(fd, "Test\n", 5);
fchmod(fd, 0644); // clears archive attribute
close(fd);

Same with facl(., SETACL, ...). The variants chmod() and acl() are not 
affected.

Regards,
Christian