tools/ocaml: Gitlab CI test for bindings

... as building and interpreting Ocaml objects in C is rather fragile.

For C producing objects for Ocaml to consume, one trick to check validity is
Gc.compact() which forces a major sweep, walking all objects.  If this doesn't
segfault, then we at least got the pointer <-> integer aspects right.

For now, start with a very simple version call.  (Re)introduce
tools/ocaml/tests and add test-ocaml-bindings which is installed into
$(DESTDIR)$(LIBEXEC)/tests to be picked up automatically with the other dom0
tests.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Andrii Sultanov <andriy.sultanov@vates.tech>

tools/ocaml/tests/bindings/.gitignore

@@ -0,0 +1 @@
+test-ocaml-bindings