ns: accept vector reference clauses; add Compiler/specials

Two general fixes shaken out by clojure/tools.macro.

- The ns macro now accepts a vector reference clause [:require …] / [:use …],
  not just the list form (:require …). Clojure dispatches on (first clause) and
  accepts both; jolt silently dropped vector clauses, so a ns written with them
  loaded with nothing required/used (tools.macro's test ns uses [:use …]).
- clojure.lang.Compiler/specials is now a static whose keys are the special-form
  symbols (matching Clojure 1.2/1.3). Macroexpansion tooling reads
  (keys Compiler/specials) to know which heads not to expand.

tools.macro itself isn't fully passing yet — its mexpand-all works, but the
macrolet/symbol-macrolet tests need letfn to macroexpand to letfn* (jolt models
letfn as a special form, not a macro over letfn*), so it stays off the list.

make test green (+1 corpus row, 0 new divergences), shakesmoke byte-identical.
One re-mint (the ns macro).

test/chez/corpus.edn

@@ -3378,4 +3378,5 @@
   {:suite "numbers / unsigned-bit-shift-right is logical over 64 bits" :label "shift of a negative shifts in zeros" :expected "[9223372036854775807 4611686018427387902]" :actual "[(unsigned-bit-shift-right -1 1) (unsigned-bit-shift-right -8 2)]"}
   {:suite "numbers / ^long is 64-bit" :label "^long comparison on a full-width long" :expected "false" :actual "((fn* ([^long a ^long b] (< a b))) 9223372036854775807 1)"}
   {:suite "numbers / ^long is 64-bit" :label "^long quot on a full-width long" :expected "3074457345618258602" :actual "((fn* ([^long a] (quot a 3))) 9223372036854775807)"}
+  {:suite "host-interop / Compiler" :label "Compiler/specials keys include the special forms" :expected "true" :actual "(every? (set (keys clojure.lang.Compiler/specials)) (quote [if do let* fn* quote def loop* recur try letfn* var]))"}
 ]