fix: repair broken linux-static build (#902)

The issue here is that the repository is owned by the user who
runs the command and the container runs as root.

Part of ooni/probe#2130

CLI/go-build-alpine

@@ -3,7 +3,10 @@ set -euxo pipefail
 apk update
 apk upgrade
 apk add --no-progress gcc git linux-headers musl-dev
-# some of the following exports are redundant but are however
+# We need to force git to look into this repository owned by the
+# user outside docker rather than by the user running docker
+git config --global --add safe.directory $(pwd)
+# Some of the following exports are redundant but are however
 # useful because they provide explicit logging
 export CGO_ENABLED=1
 export GOARM=$GOARM