flambda-backend: Fix dependencies for regenerating Flambda2 parser, tests (ocaml-flambda#1255)

Author: lukemaurer

Makefile.common-jst

@@ -95,11 +95,16 @@ duneconf/%.ws:
 $(ocamldir)/duneconf/dirs-to-ignore.inc:
 	echo "(data_only_dirs yacc $(ocaml_subdirs_to_ignore))" > $@
 
-_build/_bootinstall: Makefile.config duneconf/boot.ws duneconf/runtime_stdlib.ws duneconf/main.ws \
-	$(ocamldir)/duneconf/dirs-to-ignore.inc \
-	$(ocamldir)/duneconf/jst-extra.inc \
-	dune-project
-
+# Targets that should be prerequisites to any target that runs Dune
+dune_config_targets = \
+  duneconf/boot.ws \
+  duneconf/runtime_stdlib.ws \
+  duneconf/main.ws \
+  $(ocamldir)/duneconf/dirs-to-ignore.inc \
+  $(ocamldir)/duneconf/jst-extra.inc \
+  dune-project
+
+_build/_bootinstall: Makefile.config $(dune_config_targets)
 	echo -n '$(NATDYNLINKOPTS)' > $(ocamldir)/otherlibs/dynlink/natdynlinkops
 
 # flags.sexp