[Build Script Helper] Enable integration tests

Author: porglezomp

Utilities/build-script-helper.py

@@ -191,6 +191,7 @@ def handle_invocation(args):
     test_args += ['-Xswiftc', '-enable-testing']
     if should_test_parallel():
       test_args += ['--parallel']
+    env['SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS'] = "1"
     swiftpm('test', swift_exec, test_args, env)
   elif args.action == 'install':
     if platform.system() == 'Darwin':