packaging: Forbid compilation if the symbols file is outdated An outdated symbols file results in automatic versioned dependencies in projects which use this library. When these projects are built, shlibs:Depends cannot find a version number for the set of symbols so it uses the full version of the library package, including suffixes such as +virginia. We end up with depends lib (>== 6.0.0+virginia) instead of lib (>== 6.0.0).