Leaving config.cache/status causes autobuilders problems. config.cache and config.status are produced by GNU autoconf's configure scripts. If they are left in the source package, autobuilders may pick up settings for the wrong architecture.

The clean rule in debian/rules should remove this file. This should ideally be done by fixing the upstream build system to do it when you run the appropriate cleaning command (and don't forget to forward the fix to the upstream authors so it doesn't happen in the next release). If that is already implemented, then make sure you are indeed cleaning it in the clean rule. If all else fails, a simple rm -f should work.

Note that Lintian cannot reliably detect the removal in the clean rule, so once you fix this, please ignore or override this warning.