regtools/qeditor: replace deprecated QStyleOptionViewItemV4

...by QStyleOptionViewItem. Yes Qt got it right, in 5.7 they deprecated
QStyleOptionViewItemV4 and recommend using QStyleOptionViewItem which contains
less fields except on newer Qt where it contains all fields. Hopefully it still
works on Qt>4.x for a large enough value of x.

Change-Id: I013c383d2424b04c1c0745f0d7b1d5e62a29d324
2 files changed