LU-10026 utils: reserve fields for compress find

LU-10026 utils: reserve fields for compress find

Reserve fields for "lfs find" compressed file handling.

Fill holes in struct find_param with fp_unused members so that they
can be found more easily in the future.

Test-Parameters: trivial
Whamcloud-bug-id: EX-6856
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ic87b26a9120deb958247797512e648164b2540e5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59877
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Reviewed-by: Frederick Dilger <fdilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>