Regression from

    commit b0a391d6
    CommitDate: Tue Jan 30 23:12:04 2018 +0100

        Circular movement of cursor in a table with  hidden columns/rows, tdf#68290 related

where for nMoveX case nNewX - nCurX and nNewY - nCurY were both 0.

Also don't abuse the bMarked flag for GetNextPos() as bUnprotected
if nothing is marked, in which case also bKeepSel doesn't make
sense.

Change-Id: I59af09f1cfa397e68ce16d151ba7eee6e6598a75
Reviewed-on: https://gerrit.libreoffice.org/56935Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins