Packaging guidelines allows some libraries to be bundled, however a virtual provide must be added.

Gnulib is one of most often used libraries that were allowed to be bundled, but the majority of packages bundling it doesn't specify Provides: bundled(gnulib).

Please add the following check (or simillar):

If a package:
is a C/C++ package (CCppCheckBase), and
contains a file named 00gnulib.m4 somewhere in the directory tree, and
* doesn't specify Provides: bundled(gnulib)

then fail pointing to appropriate part of packaging guidelines.