fix build error for example/app/basic

[ywiyogo]

Fix build error zig build app_basic:

rc/App.zig:120:53: error: no field or member function named 'head' in 'basic.StopEndpoint'
                            .HEAD => self.endpoint.*.head(arena, app_context, r),
                                     ~~~~~~~~~~~~~~~^~~~~

[renerocksai]

Hi and thx for the PR! It's been superseded by #171.