prelude/python: change default value for linker args

Summary: This breaks in OSS. TODO: add a test for this

Reviewed By: JakobDegen

Differential Revision: D68809236

fbshipit-source-id: 0e5ccd236376b470b86bb0e00ee3261882f6cb24

prelude/python/toolchain.bzl

@@ -54,9 +54,9 @@ PythonToolchainInfo = provider(
         "interpreter": provider_field(typing.Any, default = None),
         "version": provider_field(typing.Any, default = None),
         "native_link_strategy": provider_field(typing.Any, default = None),
-        "linker_flags": provider_field(typing.Any, default = None),
-        "binary_linker_flags": provider_field(typing.Any, default = None),
-        "extension_linker_flags": provider_field(typing.Any, default = None),
+        "linker_flags": provider_field(list[typing.Any], default = []),
+        "binary_linker_flags": provider_field(list[typing.Any], default = []),
+        "extension_linker_flags": provider_field(list[typing.Any], default = []),
         "wheel_linker_flags": provider_field(list[typing.Any], default = []),
         "generate_static_extension_info": provider_field(typing.Any, default = None),
         "package_style": provider_field(typing.Any, default = None),