* grafana/build-container: Upgrade to Ubuntu 18.04 base image
* grafana/build-container: Upgrade to Go 1.13.4
* grafana/build-container: Upgrade to Node 10.17.0
* build: Install musl cross compilers as part of build Docker image
* build: Build also musl packages in scripts/build/build.sh
* scripts/build/build-all.sh: Build musl Linux targets
* build: Upgrade build-container to 1.2.11
* build.go: De-duplicate code
* build: Base Docker images on musl binaries
* Build: Upgrade to go 1.12.9
* Build: Use default-mysql-client for debian buster
The go base image has been updated to use Debian Buster instead of
Stretch, which seems to have done away with mysql-client in favor of
default-mysql-client.
* Build: Update Dockerfile to use go 1.12.9
Fixes#18592