Move network fuzzers from //testing/libfuzzer/fuzzers to //net

net/dns/dns_record_fuzzer.cc

 // Copyright 2015 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.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "net/dns/dns_response.h"
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   net::DnsRecordParser parser(data, size, 0);
   if (!parser.IsValid()) {
     return 0;
   }
   net::DnsResourceRecord record;
   while (parser.ReadRecord(&record)) {
   }
   return 0;
 }