Revert "[CMake] Enable CXXFLAGS to include -fsycl with benchmarks; Up…

…date Google benchmark version"

This reverts commit 99184a2.

test/bench/CMakeLists.txt

@@ -29,20 +29,14 @@ find_package(SYCL)
 set(BENCHMARK_ENABLE_TESTING OFF)
 # The icpx compiler causes errors when in release mode:
 set(BENCHMARK_ENABLE_WERROR OFF)
-
-# The -fsycl sometimes passed through CMAKE_CXX_FLAGS requires C++17 which is
-# incompatible with the C++ version required by benchmark.
-set(CMAKE_CXX_FLAGS_TMP ${CMAKE_CXX_FLAGS})
-set(CMAKE_CXX_FLAGS "")
 # Fetch googlebenchmark:
 include(FetchContent)
 FetchContent_Declare(
     googlebenchmark
     GIT_REPOSITORY https://github.com/google/benchmark.git
-    GIT_TAG v1.8.5
+    GIT_TAG v1.7.1
 )
 FetchContent_MakeAvailable(googlebenchmark)
-set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS_TMP})
 
 # Common function to add a benchmark
 set(BENCHMARK_BIN_DIR "${CMAKE_CURRENT_BINARY_DIR}")