Add new ctrl to retrieve client certificate types, print out

details in s_client.

Also add ctrl to set client certificate types. If not used sensible values
will be included based on supported signature algorithms: for example if
we don't include any DSA signing algorithms the DSA certificate type is
omitted.

Fix restriction in old code where certificate types would be truncated
if it exceeded TLS_CT_NUMBER.
(backport from HEAD)

CHANGES

@@ -8,6 +8,12 @@
      OID NID.
      [Steve Henson]
 
+  *) New ctrls to retrieve and set certificate types in a certificate
+     request message. Print out received values in s_client. If certificate
+     types is not set with custom values set sensible values based on
+     supported signature algorithms.
+     [Steve Henson]
+
   *) Support for distinct client and server supported signature algorithms.
      [Steve Henson]