Fix a couple of signedness compiler warnings, presumably due to me

using a different version of gcc from before.

[originally from svn r7627]

ssh.c

@@ -5756,7 +5756,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
              */
             s->pktout = ssh2_pkt_init(SSH2_MSG_KEXRSA_SECRET);
             ssh2_pkt_addstring_start(s->pktout);
-            ssh2_pkt_addstring_data(s->pktout, outstr, outstrlen);
+            ssh2_pkt_addstring_data(s->pktout, (char *)outstr, outstrlen);
             ssh2_pkt_send_noqueue(ssh, s->pktout);
 
 	    hash_string(ssh->kex->hash, ssh->exhash, outstr, outstrlen);

sshrsa.c

@@ -961,7 +961,7 @@ void ssh_rsakex_encrypt(const struct ssh_hash *h, unsigned char *in, int inlen,
      */
     b1 = bignum_from_bytes(out, outlen);
     b2 = modpow(b1, rsa->exponent, rsa->modulus);
-    p = out;
+    p = (char *)out;
     for (i = outlen; i--;) {
 	*p++ = bignum_byte(b2, i);
     }