For CCL, also search nx1-alphatizer definitions.

* swank-ccl.lisp (alphatizer-definitions): New
(find-definitions): Use it.
* swank-clisp.lisp (*frame-prefixes*): Update some of the patterns
for new layout.
(is-prefix-p): Use regexp matching.
(boring-frame-p): Also make compiled-tagbody compiled-block
boring.
(sldb-backtrace, %parse-stack-values): Remove code for versions
before 2.44.