gnu: sbcl-slynk: Fix the build.

* gnu/packages/lisp.scm (sbcl-slynk-boot0): Update to commit
cbf84c36c4eca8b032e3fd16177a7bc02df3ec4c.
[origin]<snippet>: Replace slynk/util references with the built system name
slynk-util. Remove compile-time invocations of slynk-require.
(sbcl-slynk-util): Inherit from sbcl-slynk-boot0.
[inputs]: Add sbcl-slynk-boot0.
[arguments]: Set an appropriate asd-file and asd-system-name.
(sbcl-slynk-arglists)[arguments]: Set an appropriate asdf-system-name.
(sbcl-slynk-fancy-inspector)[arguments]: Likewise.
(sbcl-slynk-package-fu)[arguments]: Likewise.
(sbcl-slynk-mrepl)[arguments]: Likewise.
(sbcl-slynk-trace-dialog)[arguments]: Likewise.
(sbcl-slynk-profiler)[arguments]: Likewise.
(sbcl-slynk-indentation)[arguments]: Likewise.
(sbcl-slynk-retro)[arguments]: Likewise.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>