Avoid copying release files prematurely.

Do not make `prepare_release` depend on `copy_release_files`. If
attemtping a parallel build (make -j X), this could lead Make to execute
the `copy_release_files` even before the `all_odk` target has been
completed (and thus, before all release files have been built).

So instead, we depend on `all_odk` only and we explicitly call the
`copy_release_files` target.

Author: gouttegd

template/src/ontology/Makefile.jinja2

@@ -435,7 +435,8 @@ CLEANFILES=$(MAIN_FILES) $(SRCMERGED) $(EDIT_PREPROCESSED)
 # This should be executed by the release manager whenever time comes to make a release.
 # It will ensure that all assets/files are fresh, and will copy to release folder
 .PHONY: prepare_release
-prepare_release: all_odk copy_release_files
+prepare_release: all_odk
+	$(MAKE) copy_release_files
 	rm -f $(CLEANFILES)
 	@echo "Release files are now in $(RELEASEDIR) - now you should commit, push and make a release \
         on your git hosting site such as GitHub or GitLab"