Cygwin: fstat_helper: always use handle in call to get_file_attribute

Previously, the call to get_file_attribute for FIFOs set the first
argument to NULL instead of the handle h returned by get_stat_handle,
thereby forcing the file to be opened for fetching the security
descriptor in get_file_sd().  This was done because h might have been
a pipe handle rather than a file handle, and its permissions would not
necessarily reflect those of the file.

That situation can no longer occur with the new fhandler_fifo::fstat
introduced in the previous commit.

winsup/cygwin/fhandler_disk_file.cc

@@ -475,8 +475,7 @@ fhandler_base::fstat_helper (struct stat *buf)
   else if (pc.issocket ())
     buf->st_mode = S_IFSOCK;
 
-  if (!get_file_attribute (is_fs_special () && !pc.issocket () ? NULL : h, pc,
-			   &buf->st_mode, &buf->st_uid, &buf->st_gid))
+  if (!get_file_attribute (h, pc, &buf->st_mode, &buf->st_uid, &buf->st_gid))
     {
       /* If read-only attribute is set, modify ntsec return value */
       if (::has_attribute (attributes, FILE_ATTRIBUTE_READONLY)