Support system Google Benchmark

apps/benchmarks/CMakeLists.txt

@@ -1,22 +1,28 @@
-cmake_minimum_required(VERSION 3.11)
+option(OPENMW_USE_SYSTEM_BENCHMARK "Use system Google Benchmark library." OFF)
 
-set(BENCHMARK_ENABLE_TESTING OFF)
+if(OPENMW_USE_SYSTEM_BENCHMARK)
-set(BENCHMARK_ENABLE_INSTALL OFF)
+    find_package(benchmark REQUIRED)
-set(BENCHMARK_ENABLE_GTEST_TESTS OFF)
+else()
+    cmake_minimum_required(VERSION 3.11)
 
-set(SAVED_CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    set(BENCHMARK_ENABLE_TESTING OFF)
+    set(BENCHMARK_ENABLE_INSTALL OFF)
+    set(BENCHMARK_ENABLE_GTEST_TESTS OFF)
 
-string(REPLACE "-Wsuggest-override" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    set(SAVED_CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-string(REPLACE "-Wundef" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-include(FetchContent)
-FetchContent_Declare(benchmark
-    URL https://github.com/google/benchmark/archive/refs/tags/v1.5.2.zip
-    URL_HASH MD5=49395b757a7c4656d70f1328d93efd00
-    SOURCE_DIR fetched/benchmark
-)
-FetchContent_MakeAvailableExcludeFromAll(benchmark)
 
-set(CMAKE_CXX_FLAGS "${SAVED_CMAKE_CXX_FLAGS}")
+    string(REPLACE "-Wsuggest-override" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    string(REPLACE "-Wundef" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    include(FetchContent)
+    FetchContent_Declare(benchmark
+        URL https://github.com/google/benchmark/archive/refs/tags/v1.5.2.zip
+        URL_HASH MD5=49395b757a7c4656d70f1328d93efd00
+        SOURCE_DIR fetched/benchmark
+    )
+    FetchContent_MakeAvailableExcludeFromAll(benchmark)
+
+    set(CMAKE_CXX_FLAGS "${SAVED_CMAKE_CXX_FLAGS}")
+endif()
 
 openmw_add_executable(openmw_detournavigator_navmeshtilescache_benchmark detournavigator/navmeshtilescache.cpp)
 target_compile_features(openmw_detournavigator_navmeshtilescache_benchmark PRIVATE cxx_std_17)