bridge_driver: avoid double call to VIR_FREE

While not technically a double free (since VIR_FREE NULLs the
pointer), this is unnecessary extra code.

This crept in when the function was converted from virRun to virCommand.

The AUTHORS file has also been updated.

AUTHORS

@@ -141,6 +141,7 @@ Patches have also been contributed by:
   MORITA Kazutaka      <morita.kazutaka@lab.ntt.co.jp>
   Josh Durgin          <joshd@hq.newdream.net>
   Roopa Prabhu         <roprabhu@cisco.com>
+  Paweł Krześniak      <pawel.krzesniak@gmail.com>
 
   [....send patches to get your name here....]
 

src/network/bridge_driver.c

@@ -557,7 +557,6 @@ dhcpStartDhcpDaemon(virNetworkObjPtr network)
 
     cmd = virCommandNew(DNSMASQ);
     if (networkBuildDnsmasqArgv(network, pidfile, cmd) < 0) {
-        VIR_FREE(pidfile);
         goto cleanup;
     }