macroexpand-first analyzer order; one macro path; defmacro/letfn fixes

The analyzer checked special forms before expanding macros, the reverse of the
canonical read -> macroexpand -> analyze order (Clojure/CLJS analyze-seq). Move
macroexpansion to the front of analyze-list. Knock-on fixes:

- letfn was both a (broken) macro expanding to let* AND a primitive special
  (analyze-letfn, proper letrec*). Macroexpand-first surfaced the macro, breaking
  mutual recursion; remove the macro, keep letfn a primitive.
- defmacro is now compiled by the analyzer (a :set-var-style :defmacro node that
  defs the expander fn via the fn macro — so destructuring arglists desugar — and
  marks the var a macro), so a non-top-level (when … (defmacro …)) works. The
  runtime spine's separate top-level defmacro interception is removed: one path.

SCI load 162 -> 202/218.

jolt-core/jolt/ir.clj

@@ -97,6 +97,7 @@
                                  :ret (f (get node :ret)))
       (= op :throw)  (assoc node :expr (f (get node :expr)))
       (= op :set-var) (assoc node :val (f (get node :val)))
+      (= op :defmacro) (assoc node :fn (f (get node :fn)))
       (= op :invoke) (assoc node :fn (f (get node :fn))
                                  :args (mapv f (get node :args)))
       (= op :vector) (assoc node :items (mapv f (get node :items)))