QmlJSTools: Indicate optional dependency on CppTools.

src/plugins/qmljstools/QmlJSTools.pluginspec.in

@@ -17,5 +17,7 @@ Alternatively, this plugin may be used under the terms of the GNU Lesser General
         <dependency name=\"TextEditor\" version=\"$$QTCREATOR_VERSION\"/>
         <dependency name=\"ProjectExplorer\" version=\"$$QTCREATOR_VERSION\"/>
         <dependency name=\"Locator\" version=\"$$QTCREATOR_VERSION\"/>
+        <!-- Types and modules exported from C++ will be pulled into the QML code model -->
+        <dependency name=\"CppTools\" version=\"$$QTCREATOR_VERSION\" type=\"optional\"/>
     </dependencyList>
 </plugin>