Revert "swapon/swapoff: -a returns 0 on ignored errors"

This reverts commit c9a67133d6a947532b560c7f2b9391ec299dd97f.
Revert "swapon/swapoff: size reduction, cleanup, fixes, improvements"

This reverts commit a3f326cd6619cadb44cb4bb051b1d4e54bcd3477.