QmlJs: Make "qbs" an implicit import for qbs files

We want to have qbs syntax highlighting, even if the
    import qbs
statement is missing, because we want to remove the reqirement for it.

Change-Id: I569be825440bc733c3c0fa8e146e785060e08384
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
Reviewed-by: Marco Benelli <marco.benelli@qt.io>

src/libs/qmljs/qmljsbind.h

@@ -66,6 +66,7 @@ protected:
 
     bool visit(AST::UiProgram *ast) override;
     bool visit(AST::Program *ast) override;
+    void endVisit(AST::UiProgram *) override;
 
     // Ui
     bool visit(AST::UiImport *ast) override;