GH367: Fix dsa keygen for too-short seed

If the seed value for dsa key generation is too short (< qsize),
return an error. Also update the documentation.

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

CHANGES

diff --git a/CHANGES b/CHANGES
index bcfae0a..384abf8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,10 @@
 
  Changes between 1.0.2 and 1.1.0  [xx XXX xxxx]
 
+  *) In DSA_generate_parameters_ex, if the provided seed is too short,
+     return an error
+     [Rich Salz and Ismo Puustinen <ismo.puustinen@intel.com>]
+
   *) Rewrite PSK to support ECDHE_PSK, DHE_PSK and RSA_PSK. Add ciphersuites
      from RFC4279, RFC4785, RFC5487, RFC5489.