Makefile: Set default `broker_version_requirements`

This only replaces an existing but empty `broker_version_requirements`
so it's fine in the 3.6.x branch where the parameter is never set. And
even if it is present, it would not be used by the broker so it is
harmless.

[#130992027]

Makefile

@@ -156,6 +156,7 @@ $(SOURCE_DIST): $(ERLANG_MK_RECURSIVE_DEPS_LIST)
 	$(verbose) for file in $$(find $@ -name '*.app.src'); do \
 		sed -E -i.bak \
 		  -e 's/[{]vsn[[:blank:]]*,[[:blank:]]*(""|"0.0.0")[[:blank:]]*}/{vsn, "$(PROJECT_VERSION)"}/' \
+		  -e 's/[{]broker_version_requirements[[:blank:]]*,[[:blank:]]*\[\][[:blank:]]*}/{broker_version_requirements, ["$(PROJECT_VERSION)"]}/' \
 		  $$file; \
 		rm $$file.bak; \
 	done