Re-Reland "[benchmarks] Move libcxx's fork of google/benchmark and llvm/utils'"

This reverts commit b2fbd45. D114922
fixed the reason of the 2nd revert.

This patch also re-applies 39e9f5d.

Differential Revision: https://reviews.llvm.org/D112012

Author: mtrofin

libc/benchmarks/CMakeLists.txt

@@ -17,7 +17,7 @@ string(REPLACE ";" " " GOOGLE_BENCHMARK_TARGET_FLAGS "${GOOGLE_BENCHMARK_TARGET_
 ExternalProject_Add(google-benchmark
     EXCLUDE_FROM_ALL ON
     PREFIX google-benchmark
-    SOURCE_DIR ${LIBC_SOURCE_DIR}/../llvm/utils/benchmark
+    SOURCE_DIR ${LLVM_THIRD_PARTY_DIR}/benchmark
     INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/google-benchmark
     CMAKE_CACHE_ARGS
         -DBUILD_SHARED_LIBS:BOOL=OFF

libc/benchmarks/LibcBenchmark.cpp

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

libcxx/benchmarks/CMakeLists.txt

@@ -41,7 +41,7 @@ ExternalProject_Add(google-benchmark-libcxx
         EXCLUDE_FROM_ALL ON
         DEPENDS cxx cxx-headers
         PREFIX benchmark-libcxx
-        SOURCE_DIR ${LIBCXX_SOURCE_DIR}/utils/google-benchmark
+        SOURCE_DIR ${LLVM_THIRD_PARTY_DIR}/benchmark
         INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/benchmark-libcxx
         CMAKE_CACHE_ARGS
           -DCMAKE_C_COMPILER:STRING=${CMAKE_C_COMPILER}
@@ -66,7 +66,7 @@ if (LIBCXX_BENCHMARK_NATIVE_STDLIB)
   ExternalProject_Add(google-benchmark-native
         EXCLUDE_FROM_ALL ON
         PREFIX benchmark-native
-        SOURCE_DIR ${LIBCXX_SOURCE_DIR}/utils/google-benchmark
+        SOURCE_DIR ${LLVM_THIRD_PARTY_DIR}/benchmark
         INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/benchmark-native
         CMAKE_CACHE_ARGS
           -DCMAKE_C_COMPILER:STRING=${CMAKE_C_COMPILER}