This will fix link issue associated with extension:

//--------
Scanning dependencies of target ConfigureAdditionalLauncherSettings
[  4%] Configuring: AdditionalLauncherSettings.ini
[  4%] Built target ConfigureAdditionalLauncherSettings
Scanning dependencies of target vtkSlicerLoadableExtensionTemplateModuleLogic
[  8%] Building CXX object Logic/CMakeFiles/vtkSlicerLoadableExtensionTemplateModuleLogic.dir/vtkSlicerLoadableExtensionTemplateLogic.cxx.o
c++: --no-undefined: linker input file unused because linking not done
Linking CXX shared library ../lib/Slicer-4.1/qt-loadable-modules/libvtkSlicerLoadableExtensionTemplateModuleLogic.so
/usr/bin/ld: cannot find -lQtTesting
//--------

See http://slicer.cdash.org/viewBuildError.php?buildid=17278

git-svn-id: http://svn.slicer.org/Slicer4/trunk@19974 3bd1e089-480b-0410-8dfb-8563597acbee