Bug#683398: FTBFS: build-indep needed for binary-arch

[Peter Samuelson]

Package: cmucl
Version: 20c-2
Severity: important

The cmucl build is split into build-arch and build-indep, but
build-indep builds doc files that appear in arch-dependent packages.

This issue would cause a buildd to fail.  Because it is a single-arch
package, it is not normally autobuilt, but a binNMU may someday be
needed and it will fail then.