LU-16944 utils: lfs find: handle multiple paths correctly

LU-16944 utils: lfs find: handle multiple paths correctly

When lfs find is used with multiple paths and the first non-path
option is a '!' or an option without an argument like '-print',
the code skipped the final path because it assumed that the first
non-path option would be an option with an argument.

This commit resolves the bug by remembering the last-processed argv
index so that the index of the final path argument is correct whether
the next option consumes 2 indexes or just 1.

Signed-off-by: Thomas Bertschinger <bertschinger@lanl.gov>
Change-Id: I03133a43641af7a53a20d947b8ef82529e453251
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51578
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>