Prevent package from including Mac Metadata file (#640)

* Prevent package from including Mac Metadata file

If `tar` is run from a macOS, by default, it will create Mac Metadata
file for every file and folder which starts with ".". This change makes
sure that the archives does not include Mac Metadata file.

Author: chkuang-g

source/ExportUnityPackage/export_unity_package.py

@@ -2595,6 +2595,9 @@ def create_archive(archive_filename, input_directory, timestamp):
                 os.utime(filename, (FLAGS.timestamp, FLAGS.timestamp))
             # Don't recurse directories.
             tar_args.append("-n")
+            # Avoid creating mac metadata files with name started with "."
+            if platform.system() == "Darwin":
+              tar_args.append("--no-mac-metadata")
           tar_args.extend(["-T", list_filename])
           # Disable timestamp in the gzip header.
           tar_env = os.environ.copy()