contrib: add build-script for GitHub actions

contrib/actions/run-build.sh

+#!/bin/bash
+
+sudo apt install git subversion build-essential python gawk unzip libncurses5-dev zlib1g-dev libssl-dev wget time
+
+export BROKEN=1
+export GLUON_DEPRECATED=1
+export GLUON_SITEDIR="contrib/ci/minimal-site"
+export GLUON_TARGET=$1
+
+make update
+make -j2
+