https://github.com/grafana/loki/pull/49 broke promtail with
standard_init_linux.go:178: exec user process caused "no such file or directory"

From https://medium.com/@diogok/on-golang-static-binaries-cross-compiling-and-plugins-1aed33499671


CGO_ENABLED=0 makes it static, afaics

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>