Fix build of ctkTestApplication.cpp with Qt4. Fixes #482
Fix build of ctkTestApplication.cpp with Qt4. Fixes #482

This commit fixes windows build error originally introduced by
commit 77a4db54 adding support for Qt5.

Example of errors:

31>6>4>..\..\..\..\CTK\Libs\Widgets\ctkTestApplication.cpp(129) : error C2228: left of '.toLocal8Bit' must have class/struct/union
31>6>4>        type is 'const char *'

msmolens/CTK,laurennlam/CTK,laurennlam/CTK,Sardge/CTK,sankhesh/CTK,msmolens/CTK,danielknorr/CTK,AndreasFetzer/CTK,ddao/CTK,laurennlam/CTK,pieper/CTK,pieper/CTK,naucoin/CTK,AndreasFetzer/CTK,jcfr/CTK,mehrtash/CTK,SINTEFMedtek/CTK,rkhlebnikov/CTK,mehrtash/CTK,sankhesh/CTK,fedorov/CTK,msmolens/CTK,ddao/CTK,commontk/CTK,rkhlebnikov/CTK,ddao/CTK,sankhesh/CTK,AndreasFetzer/CTK,mehrtash/CTK,jcfr/CTK,naucoin/CTK,Heather/CTK,mehrtash/CTK,naucoin/CTK,danielknorr/CTK,laurennlam/CTK,pieper/CTK,CJGoch/CTK,naucoin/CTK,SINTEFMedtek/CTK,commontk/CTK,Heather/CTK,151706061/CTK,Heather/CTK,CJGoch/CTK,CJGoch/CTK,SINTEFMedtek/CTK,fedorov/CTK,danielknorr/CTK,151706061/CTK,rkhlebnikov/CTK,AndreasFetzer/CTK,sankhesh/CTK,CJGoch/CTK,msmolens/CTK,pieper/CTK,Sardge/CTK,Sardge/CTK,danielknorr/CTK,fedorov/CTK,ddao/CTK,jcfr/CTK,SINTEFMedtek/CTK,jcfr/CTK,fedorov/CTK,rkhlebnikov/CTK,Sardge/CTK,commontk/CTK,151706061/CTK,SINTEFMedtek/CTK,Heather/CTK,151706061/CTK,commontk/CTK,151706061/CTK,jcfr/CTK,CJGoch/CTK