agent_connect_unix: make sure there's a trailing zero

... if the path name was too long. Reported by Coverity CID 89801.

src/agent.c

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2009 by Daiki Ueno
- * Copyright (C) 2014 by Daniel Stenberg
+ * Copyright (C) 2010-2014 by Daniel Stenberg
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms,
@@ -159,6 +159,8 @@ agent_connect_unix(LIBSSH2_AGENT *agent)
 
     s_un.sun_family = AF_UNIX;
     strncpy (s_un.sun_path, path, sizeof s_un.sun_path);
+    s_un.sun_path[sizeof(s_un.sun_path)-1]=0; /* make sure there's a trailing
+                                                 zero */
     if (connect(agent->fd, (struct sockaddr*)(&s_un), sizeof s_un) != 0) {
         close (agent->fd);
         return _libssh2_error(agent->session, LIBSSH2_ERROR_AGENT_PROTOCOL,