Moved dependency on QtHelp

Necessary because the CppHoverHandler uses QtHelp and moved from
CppTools to CppEditor.

src/plugins/cppeditor/cppeditor.pro

 TEMPLATE = lib
 TARGET = CppEditor
 DEFINES += CPPEDITOR_LIBRARY
+CONFIG += help
 include(../../libs/utils/utils.pri)
 include(../../qworkbenchplugin.pri)
 include(cppeditor_dependencies.pri)

src/plugins/cpptools/cpptools.pro

@@ -8,7 +8,6 @@ include(cpptools_dependencies.pri)
 DEFINES += QT_NO_CAST_TO_ASCII
 INCLUDEPATH += .
 DEFINES += CPPTOOLS_LIBRARY
-CONFIG += help
 HEADERS += cpptools_global.h \
     cppquickopenfilter.h \
     cppclassesfilter.h \