Fix the archive_build step for Win x64.

scripts/slave/recipes/chromium.expected/full_chromium_Win_x64.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\kill_processes.py"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "taskkill"
   },
@@ skipping 198 matching lines @@
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\slave\\chromium\\archive_build.py",
       "--target",
-      "Release",
+      "Release_x64",
       "--factory-properties",
       "{\"gclient_env\": {\"GYP_DEFINES\": \"chromium_win_pch=0 component=static_library fastbuild=1 gomadir='[BUILD]\\\\goma' linux_dump_symbols=0 target_arch=x64 test_isolation_mode=noop use_goma=1\"}, \"gs_acl\": \"public-read\", \"gs_bucket\": \"gs://chromium-browser-snapshots\"}",
       "--build-properties",
       "{\"got_angle_revision\": \"fac9503c46405f77757b9a728eb85b8d7bc6080c\", \"got_angle_revision_cp\": \"refs/heads/master@{#297276}\", \"got_nacl_revision\": \"d998e125e8253980d76e269b7982aeeefc1b9b50\", \"got_nacl_revision_cp\": \"refs/heads/master@{#274981}\", \"got_revision\": \"f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9\", \"got_revision_cp\": \"refs/heads/master@{#170242}\", \"got_swarming_client_revision\": \"a0ee5d99f1d4b38ddaa4c759c837980b63b99566\", \"got_swarming_client_revision_cp\": \"refs/heads/master@{#276089}\", \"got_v8_revision\": \"801ada225ddc271c132c3a35f03975671d43e399\", \"got_v8_revision_cp\": \"refs/heads/master@{#43426}\", \"got_webrtc_revision\": \"0f90628433546e61d9268596da93418c623137f4\", \"got_webrtc_revision_cp\": \"refs/heads/master@{#120644}\"}",
       "--mode",
       "dev"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "archive_build"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]