x_labels are no places next to values

```python
config = pygal.Config(
fill=True,
show_legend=False,
print_zeroes=False,
print_values=True,
print_labels=False,
print_values_position='top'
)
bar_chart = pygal.HorizontalBar(config)
bar_chart.add('', 1)
bar_chart.add('', 0)
bar_chart.add('', 4)
bar_chart.add('', 5)
bar_chart.add('', 3)
bar_chart.add('', 2)
```


```python
config = pygal.Config(
fill=True,
show_legend=False,
print_zeroes=False,
print_values=True,
print_labels=False,
print_values_position='top'
)
bar_chart = pygal.HorizontalBar(config)
bar_chart.add('', 1)
bar_chart.add('', 0)
bar_chart.add('', 4)
bar_chart.add('', 5)
bar_chart.add('', 3)
bar_chart.add('', 2)
bar_chart.x_labels = ['a','b','c','d','e','f']
```


Start by running the two Python snippets against pygal and compare the HorizontalBar output with and without x_labels. Trace the label and value positioning used by HorizontalBar, then add a regression test for the reproduced case. Done means x_labels are placed next to their corresponding values without breaking the existing output.

Written by the indexing model from the issue text.