ios: Allow bot configs to set extra env variables

scripts/slave/recipes/ios/unified_builder_tester.py

 # 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.
 
 DEPS = [
   'ios',
   'platform',
   'properties',
 ]
 
@@ skipping 13 matching lines @@
       buildnumber='0',
       mastername='chromium.fake',
       slavename='fake-vm',
     )
     + api.ios.make_test_build_config({
       'xcode version': 'fake xcode version',
       'GYP_DEFINES': {
         'fake gyp define 1': 'fake value 1',
         'fake gyp define 2': 'fake value 2',
       },
+      'env': {
+        'fake env var 1': 'fake env value 1',
+        'fake env var 2': 'fake env value 2',
+      },
       'compiler': 'xcodebuild',
       'configuration': 'Debug',
       'sdk': 'iphonesimulator8.0',
       'tests': [
         {
           'app': 'fake tests 1',
           'device type': 'fake device',
           'os': '8.0',
         },
         {
@@ skipping 160 matching lines @@
     )
     + api.step_data(
       'fake tests 3 (fake device iOS 8.1)',
       retcode=1
     )
     + api.step_data(
       'fake tests 5 (fake device iOS 8.1)',
       retcode=2
     )
   )