Pausetimes available for all 5.X OCaml

Makefile

@@ -108,6 +108,7 @@ ifeq (1, $(USE_SYS_DUNE_HACK))
 	ln -s $(SYS_DUNE_BASE_DIR)/lib/dune $(CURDIR)/_opam/sys_dune/lib/dune
 	opam install --switch=$(CONFIG_SWITCH_NAME) --yes ocamlfind
 	opam install --switch=$(CONFIG_SWITCH_NAME) --yes "dune.$(SANDMARK_DUNE_VERSION)" "dune-configurator.$(SANDMARK_DUNE_VERSION)"
+	# Pin the version so it doesn't change when installing packages
 	opam pin add --switch=$(CONFIG_SWITCH_NAME) --yes -n dune "$(SANDMARK_DUNE_VERSION)"
 endif
 
@@ -153,10 +154,18 @@ _opam/%: _opam/opam-init/init.sh ocaml-versions/%.json
 override_packages/%: setup_sys_dune/%
 	$(eval CONFIG_SWITCH_NAME = $*)
 	$(eval DEV_OPAM = $(OPAMROOT)/$(CONFIG_SWITCH_NAME)/share/dev.opam)
+	# Retrieve set of version constraints for chosen OCaml version
 	@{ case "$*" in \
 		*5.1.0*) echo "Using new template" && cp dependencies/template/dev-5.1.0+trunk.opam $(DEV_OPAM) ;; \
 		*) echo "Using old template" && cp dependencies/template/dev.opam $(DEV_OPAM) ;; \
 	esac };
+	# Conditionally install runtime_events_tools for olly (pausetimes)
+	@{ case "$*" in \
+		5.*) \
+			echo "Enabling pausetimes for OCaml >= 5" \
+			PACKAGES += runtime_events_tools ;; \
+	    *) echo "Pausetimes unavailable for OCaml < 5" ;; \
+	esac };
 	opam repo add upstream "git+https://github.com/ocaml/opam-repository.git" --on-switch=$(CONFIG_SWITCH_NAME) --rank 2
 	opam repo add alpha git+https://github.com/kit-ty-kate/opam-alpha-repository.git --on-switch=$(CONFIG_SWITCH_NAME) --rank 2
 	opam exec --switch $(CONFIG_SWITCH_NAME) -- opam update

dependencies/template/dev-5.1.0+trunk.opam

@@ -39,5 +39,4 @@ depends: [
   "stdlib-shims" {= "0.1.0"}
   "uri" {= "4.1.0"}
   "zarith" {= "1.10"}
-  "runtime_events_tools"
 ]