T5400: initialize OPAM environment where it's really needed

Instead of trying to fix - what we call - "Schroedingers build environment"
in the outside world calling this package build, we should rather fix the
Makefile/build system..

Author: c-po

.github/workflows/package-smoketest.yml

@@ -44,7 +44,6 @@ jobs:
           repository: ${{ github.event.pull_request.head.repo.full_name }}
       - name: Build vyos-1x package
         run: |
-          eval $(opam env --root=/opt/opam --set-root)
           cd packages/vyos-1x; dpkg-buildpackage -uc -us -tc -b
       - name: Generate ISO version string
         id: version

Makefile

@@ -28,7 +28,7 @@ libvyosconfig:
 			git clone https://github.com/vyos/libvyosconfig.git /tmp/libvyosconfig || exit 1
 		cd /tmp/libvyosconfig && \
 			git checkout 677d1e2bf8109b9fd4da60e20376f992b747e384 || exit 1
-		./build.sh
+		eval $$(opam env --root=/opt/opam --set-root) && ./build.sh
 	fi
 
 .PHONY: interface_definitions