Move multithreading patch up so that it's working in the GUI

Bypass an issue with `cx-freeze` that fails to include the
`fitz._wxcolors` module in the final Windows artifact.

dangerzone/__init__.py

@@ -4,6 +4,12 @@ import sys
 
 logger = logging.getLogger(__name__)
 
+# Call freeze_support() to avoid passing unknown options to the subprocess.
+# See https://github.com/freedomofpress/dangerzone/issues/873
+import multiprocessing
+
+multiprocessing.freeze_support()
+
 
 try:
     from . import vendor  # type: ignore [attr-defined]

dangerzone/gui/__init__.py

@@ -10,6 +10,7 @@ from typing import List, Optional
 import click
 import colorama
 
+
 # FIXME: See https://github.com/freedomofpress/dangerzone/issues/320 for more details.
 if typing.TYPE_CHECKING:
     from PySide2 import QtCore, QtGui, QtWidgets

dangerzone/gui/main_window.py

@@ -3,7 +3,6 @@ import os
 import platform
 import tempfile
 import typing
-from multiprocessing import freeze_support
 from multiprocessing.pool import ThreadPool
 from pathlib import Path
 from typing import List, Optional
@@ -1238,9 +1237,6 @@ class DocumentsListWidget(QtWidgets.QListWidget):
     def start_conversion(self) -> None:
         if not self.thread_pool_initized:
             max_jobs = self.dangerzone.isolation_provider.get_max_parallel_conversions()
-            # Call freeze_support() to avoid passing unknown options to the subprocess.
-            # See https://github.com/freedomofpress/dangerzone/issues/873
-            freeze_support()
             self.thread_pool = ThreadPool(max_jobs)
 
         for doc in self.docs_list:

setup-windows.py

@@ -13,7 +13,7 @@ setup(
     description="Dangerzone",
     options={
         "build_exe": {
-            "packages": ["dangerzone", "dangerzone.gui"],
+            "packages": ["dangerzone", "dangerzone.gui", "pymupdf._wxcolors"],
             "excludes": ["test", "tkinter"],
             "include_files": [("share", "share"), ("LICENSE", "LICENSE")],
             "include_msvcr": True,