[compat] Let PyInstaller detect _legacy module

yt_dlp/compat/__init__.py

@@ -8,14 +8,8 @@ from ._deprecated import *  # noqa: F401, F403
 from .compat_utils import passthrough_module
 
 # XXX: Implement this the same way as other DeprecationWarnings without circular import
-try:
-    passthrough_module(__name__, '._legacy', callback=lambda attr: warnings.warn(
-        DeprecationWarning(f'{__name__}.{attr} is deprecated'), stacklevel=2))
-    HAS_LEGACY = True
-except ModuleNotFoundError:
-    # Keep working even without _legacy module
-    HAS_LEGACY = False
-del passthrough_module
+passthrough_module(__name__, '._legacy', callback=lambda attr: warnings.warn(
+    DeprecationWarning(f'{__name__}.{attr} is deprecated'), stacklevel=2))
 
 
 # HTMLParseError has been deprecated in Python 3.3 and removed in
@@ -76,3 +70,9 @@ if compat_os_name in ('nt', 'ce'):
         return userhome + path[i:]
 else:
     compat_expanduser = os.path.expanduser
+
+
+# NB: Add modules that are imported dynamically here so that PyInstaller can find them
+# See https://github.com/pyinstaller/pyinstaller-hooks-contrib/issues/438
+if False:
+    from . import _legacy  # noqa: F401