Revert "[libc][NFC][Obvious] Fix the benchmarks after the switch to llvm/third-party"

This reverts commit 39e9f5d.

Reverting, as we needed to re-revert the benchmarks move because it was
causing a build failure in the Fuchsia bots due to the way they consume
libcxx's CMakeLists. I want to make sure I understand where the fix
should be for that. After that, I'll incorporate the change here in the
re-reland.

Author: mtrofin

libc/benchmarks/LibcBenchmark.cpp

@@ -15,7 +15,7 @@ namespace libc_benchmarks {
 
 void checkRequirements() {
   const auto &CpuInfo = benchmark::CPUInfo::Get();
-  if (CpuInfo.scaling == benchmark::CPUInfo::ENABLED)
+  if (CpuInfo.scaling_enabled)
     report_fatal_error(
         "CPU scaling is enabled, the benchmark real time measurements may be "
         "noisy and will incur extra overhead.");