SSH: use the port number as well for known_known checks

... if the libssh2 version is new enough.

Bug: http://curl.haxx.se/bug/view.cgi?id=1448

lib/ssh.c

@@ -99,6 +99,13 @@
 #  endif
 #endif
 
+/* Feature detection based on version numbers to better work with
+   non-configure platforms */
+#if LIBSSH2_VERSION_NUM >= 0x010206
+/* libssh2_knownhost_checkp was added in 1.2.6 */
+#define HAVE_LIBSSH2_KNOWNHOST_CHECKP
+#endif
+
 #ifndef PATH_MAX
 #define PATH_MAX 1024 /* just an extra precaution since there are systems that
                          have their definition hidden well */
@@ -546,13 +553,25 @@ static CURLcode ssh_knownhost(struct connectdata *conn)
       keybit = (keytype == LIBSSH2_HOSTKEY_TYPE_RSA)?
         LIBSSH2_KNOWNHOST_KEY_SSHRSA:LIBSSH2_KNOWNHOST_KEY_SSHDSS;
 
+#ifdef HAVE_LIBSSH2_KNOWNHOST_CHECKP
+      keycheck = libssh2_knownhost_checkp(sshc->kh,
+                                          conn->host.name,
+                                          (conn->remote_port != PORT_SSH)?
+                                          conn->remote_port:-1,
+                                          remotekey, keylen,
+                                          LIBSSH2_KNOWNHOST_TYPE_PLAIN|
+                                          LIBSSH2_KNOWNHOST_KEYENC_RAW|
+                                          keybit,
+                                          &host);
+#else
       keycheck = libssh2_knownhost_check(sshc->kh,
                                          conn->host.name,
                                          remotekey, keylen,
                                          LIBSSH2_KNOWNHOST_TYPE_PLAIN|
                                          LIBSSH2_KNOWNHOST_KEYENC_RAW|
                                          keybit,
                                          &host);
+#endif
 
       infof(data, "SSH host check: %d, key: %s\n", keycheck,
             (keycheck <= LIBSSH2_KNOWNHOST_CHECK_MISMATCH)?