[libc] [llvm] [libc] Add more functions in CPP/bit.h (PR #73814)

[via llvm-commits]

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@@ -1,57 +1,261 @@
-//===-- Freestanding version of bit_cast  -----------------------*- C++ -*-===//
+//===-- Implementation of the C++20 bit header  -----------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+// This is inspired from LLVM ADT/bit.h header.
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michaelrj-google wrote:

nit: "inspired by"

https://github.com/llvm/llvm-project/pull/73814