Fixing DSA key pair generation

generator of 0 mustn't be accepted.

Author: ktakashi

ext/crypto/sagittarius/crypto/keys/operations/asymmetric/dsa.scm

@@ -194,7 +194,7 @@
       (let loop ()
 	(let* ((h (random-range 2 (- p 2)))
 	       (g (mod-expt h e p)))
-	  (if (= g 1)
+	  (if (or (= g 1) (zero? g))
 	      (loop)
 	      g)))))