add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/kernel/cgroup/legacy_freezer.c
..
..
@@ -479,3 +479,4 @@
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 	.fork		= freezer_fork,
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 	.legacy_cftypes	= files,
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 };
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+EXPORT_SYMBOL_GPL(freezer_cgrp_subsys);