Fix a small memory leak when parsing unix: ports twice

Fixes bug 23053; CID 1415725.

changes/bug23053

@@ -0,0 +1,5 @@
+  o Minor bugfixes (memory leak):
+    - Fix a small memory leak when validating a configuration that
+      uses two or more AF_UNIX sockets for the same port type.
+      Fixes bug 23053; bugfix on 0.2.6.3-alpha. This is CID
+      1415725.

src/or/config.c

@@ -6877,6 +6877,7 @@ parse_port_config(smartlist_t *out,
     SMARTLIST_FOREACH(elts, char *, cp, tor_free(cp));
     smartlist_clear(elts);
     tor_free(addrport);
+    tor_free(unix_socket_path);
   }
 
   if (warn_nonlocal && out) {