This fixes the exact same build error reported at [0].
Upstream fixed it too, see [1], but I decided to use the minimal patch
until a new version is released instead.

[0] https://github.com/golang/go/issues/29281
[1] https://github.com/prometheus/statsd_exporter/pull/171

Signed-off-by: Andre Heider <a.heider@gmail.com>