Fix compile with Qt 5.7

[shumski]

bsc#1001141

[mvidner]

Thanks! I have created a Bugzilla ticket for this so that we can include the fix in SLE too.

[shundhammer]

LGTM

[shundhammer]

Background: When not-that-important Qt classes might become binary incompatible because they are not PIMPL'ed and they need some more data members, they introduce a new one like that QStyleOptionProgressBarV2, so newer code can use that one with the added data member, while old code remains working with the unchanged class.

When a new Qt version (a new major release) comes along, they simply rename the latest V2 (or later) version to the normal name without V2 and they deprecate V2, V3 etc. so they can use it again in the new major release.

That ...V2 here probably goes back to Qt4.

[mvidner]

A fixup was needed because we keep the version number in 3 places: a60ca09