Integrate my implementation of a countermeasure against

Bleichenbacher's DSA attack.  With this implementation, the expected
number of iterations never exceeds 2.

New semantics for BN_rand_range():
BN_rand_range(r, min, range) now generates r such that
     min <= r < min+range.
(Previously, BN_rand_range(r, min, max) generated r such that
     min <= r < max.
It is more convenient to have the range; also the previous
prototype was misleading because max was larger than
the actual maximum.)

crypto/dsa/dsa_ossl.c

@@ -179,7 +179,9 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 	kinv=NULL;
 
 	/* Get random k */
-	if (!BN_rand_range(&k, BN_value_one(), dsa->q)) goto err;
+	do
+		if (!BN_rand_range(&k, NULL, dsa->q)) goto err;
+	while (BN_is_zero(&k));
 
 	if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 		{