Fix up warning due to missing declarations.

remoting/tools/client_webserver/main.c

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Simple webserver that returns empty content with the requested mimetype.
 //
 // For example:
 //   http://localhost:8080/pepper-application/x-chromoting-plugin
 // Will return empty content, but with the requested mimetype:
 //   Content-Type: pepper-application/x-chromoting-plugin
 //
 // This is useful for testing the Chromoting plugin while we wait for
 // updated mimetype support to be added to Chrome.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/wait.h>
 #include <netinet/in.h>
+#include <unistd.h>
 
 #define PORT 8080
 
 void error(const char *msg) {
   fprintf(stderr, "ERROR - %s\n", msg);
   exit(1);
 }
 
 // Read text data from a socket to a buffer.
 // Data up to the next \n char is read into the buffer.
@@ skipping 125 matching lines @@
     } else {
       // Parent process.
       if (close(connection) < 0) {
         error("Unable to close connection in parent");
       }
     }
   }
 
   return 0;
 }