2.26.61: Upgrade tweak for ECL. Small refactoring for lisp-build.
ECL output-files semantics has changed, so unintern the old one rather than conflict. Rename *compile-op-compile-file-function* to just *compile-file-function*. Factor all the lisp build perform's through perform-lisp-FOO, so they can be shared with concatenated targets that are not cl-source-file without fighting default methods and class inheritance.