[Development] abi breakage for qtwebengine libraries in 5.9

[Allan Sandfeld Jensen]

On Friday 05 May 2017, Michal Klocek wrote:
> Hi
> 
> With 5.8.0 we released web engine libs which export operator new , new[]
> , delete, delete[] globally, unfortunately the issue was not spotted in
> time.
> 
> https://bugreports.qt.io/browse/QTBUG-60565
> 
> With 5.9.0 we plan to correct the issue, unfortunately everything which
> was compiled against qtwebengine 5.8.0 will be broken when used with
> 5.9.0 libraries due to missing symbols and needs to be recompiled.
> 
Note that this primarily affects Linux, but since BC is mainly important for 
Linux that doesn't help much.

The issue trigger because Qt exports symbols with the Qt_5 tag, so 
applications that used the overridden new/delete operators will be looking not 
just for new and delete, but new and delete with the Qt_5 tag.

Best regards
`Allan