[libc++] Make parameter names consistent and enforce the naming style using readability-identifier-naming

Ensure that parameter names have the style `__lower_case`

Reviewed By: ldionne, #libc

Spies: aheejin, sstefan1, libcxx-commits, miyuki

Differential Revision: https://reviews.llvm.org/D129051

NOKEYCHECK=True
GitOrigin-RevId: b48c5010a46246cc3337244f7e2736dacf5889dc
diff --git a/include/condition_variable b/include/condition_variable
index dfcb716..92088f3 100644
--- a/include/condition_variable
+++ b/include/condition_variable
@@ -261,7 +261,7 @@
 }
 
 _LIBCPP_FUNC_VIS
-void notify_all_at_thread_exit(condition_variable& cond, unique_lock<mutex> lk);
+void notify_all_at_thread_exit(condition_variable&, unique_lock<mutex>);
 
 _LIBCPP_END_NAMESPACE_STD