Fix 21190 - misplaced ledger lines for whole notes

Fix 21190 - misplaced ledger lines for whole notes

Fixed by computing a stem x-position in Chord::layoutPitched() which corresponds to the actual chord note widths and positions, rather than relying on a global, fixed value (score()->noteHeadWidth() ).

For details, see http://musescore.org/en/node/21190