unbundle gtest
set gnu++17 for >=gtest-1.17
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,7 +27,7 @@ find_package(Threads)
 
 option(BUILD_SHARED_LIBS "Build shared libraries" ON)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 17)
 
 if(BUILD_SHARED_LIBS)
   set(CMAKE_C_VISIBILITY_PRESET hidden)
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,13 +1,3 @@
-include(GoogleTest)
-
-set(BUILD_GMOCK OFF CACHE BOOL "" FORCE)
-set(INSTALL_GTEST OFF CACHE BOOL "" FORCE)
-mark_as_advanced(BUILD_GMOCK INSTALL_GTEST GTEST_HAS_ABSL)
-
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-
-add_subdirectory("${PROJECT_SOURCE_DIR}/src/3rdparty/googletest" "test/3rdparty/googletest")
-
 add_executable(all_tests 
   $<TARGET_OBJECTS:chromaprint_objs>
   main.cpp
@@ -35,8 +25,10 @@ add_executable(all_tests
   ../src/utils/rolling_integral_image_test.cpp
 )
 
+find_package(GTest REQUIRED)
+include(GoogleTest)
 target_include_directories(all_tests PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
-target_link_libraries(all_tests PRIVATE chromaprint gtest gtest_main)
+target_link_libraries(all_tests PRIVATE chromaprint GTest::gtest_main)
 
 if(BUILD_TOOLS)
   target_sources(all_tests PRIVATE ../src/audio/ffmpeg_audio_reader_test.cpp)