* guix/build/asdf-build-system.scm (copy-files-to-output): Don't attempt to
reset timestamps on files without write access.
(install): When parent SBCL package is in the inputs, use its source. This
way we get possibly patched sources in CL packages as well (e.g. for FFI).
This is also useful for sources that generate files on load-op, like cl-unicode.
* guix/build-system/asdf.scm (package-with-build-system): Forward the SBCL
parent as a native input so that it can be used in the above install phase.
c3f1f09586