Fixes for emacs 23 and cmucl

* slime.el (define-slime-contrib): Avoid some funky emacs23 issue
with cl-labels.

* swank-loader.lisp (module-binary-dir): CMUCL doesn't always have
strings as directory components.

* swank.lisp (swank-require): Shouldn't even need this, but push
upper-case version of string into *MODULES*.