Keep opam-dune-lint happy

The OxCaml tests are using libraries stdlib_stable and
stdlib_upstream_compatible which are only provided by OxCaml.

Author: vouillon

.github/workflows/lint.yml

@@ -28,6 +28,7 @@ jobs:
       - name: Install faked binaryen-bin package
         # It's faster to use a cached version
         run: opam install --fake binaryen-bin
+      - run: sh tools/make_opam_dune_lint_dir.sh
       - uses: ocaml/setup-ocaml/lint-opam@v3
 
   lint-fmt:

tools/make_opam_dune_lint_dir.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# Define empty libraries stdlib_stable and stdlib_upstream_compatible
+# to keep opam-dune-lint happy (these libraries are OxCaml-specific).
+
+mkdir opam_dune_lint_dir && cd opam_dune_lint_dir
+echo "(lang dune 3.20)" > dune-project
+touch stdlib_stable.opam
+touch stdlib_upstream_compatible.opam
+cat > dune <<EOF
+(library (public_name stdlib_stable))
+(library (public_name stdlib_upstream_compatible))
+EOF