QmlJS: Fix qbs build.

Change-Id: I6264b0a50ae87fd18d6a3fe8230e29abf8e77b0d
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>

src/libs/qmljs/qmljs.qbs

@@ -92,6 +92,7 @@ QtcLibrary {
     }
 
     Export {
+        Depends { name: "CPlusPlus" }
         Depends { name: "LanguageUtils" }
     }
 }