verify: rename "hasmanifest" variable for source code readability Before this patch, there are two ambiguous variables: "havemf" and "hasmanifest". "havemf" means whether there are any "manifest" entries. "hasmanifest" means whether there are any "changelog" entries referring to "manifest" entry. This patch renames from "hasmanifest" to "refersmf" to clear difference from "havemf".