bundle up Unix SET_PATH_INFO args into a struct and change name

We'd like to be able to use the unix SET_PATH_INFO_BASIC args to set
file times as well, but that makes the argument list rather long. Bundle
up the args for unix SET_PATH_INFO call into a struct. For now, we don't
actually use the times fields anywhere. That will be done in a follow-on
patch.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>