GH367: use random data if seed too short.

Signed-off-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>

crypto/dsa/dsa_gen.c

@@ -203,7 +203,7 @@ int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
             if (!BN_GENCB_call(cb, 0, m++))
                 goto err;
 
-            if (!seed_len) {
+            if (!seed_len || !seed_in) {
                 if (RAND_pseudo_bytes(seed, qsize) < 0)
                     goto err;
                 seed_is_random = 1;