Define *print-meta* as a bindable dynamic var

clojure.core/*print-meta* was missing, so (binding [*print-meta* true] …) failed
to compile ("var of non-var"). Add it (default false, like the JVM); corpus
covers binding it.

host/chez/dynamic-var-defaults.ss

@@ -25,3 +25,6 @@
 
 ;; *print-readably* — bound by pr-family / with-out-str-style code; default true.
 (def-var! "clojure.core" "*print-readably*" #t)
+
+;; *print-meta* — when true, pr prints metadata with a ^ prefix; default false.
+(def-var! "clojure.core" "*print-meta*" #f)