use -std=c++17

build/cmake_modules/CheckAtomic.cmake

@@ -8,7 +8,7 @@ INCLUDE(CheckLibraryExists)
 
 function(check_working_cxx_atomics varname)
   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
-  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11")
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++17")
   CHECK_CXX_SOURCE_COMPILES("
 #include <atomic>
 std::atomic<int> x;
@@ -25,7 +25,7 @@ endfunction(check_working_cxx_atomics)
 
 function(check_working_cxx_atomics64 varname)
   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
-  set(CMAKE_REQUIRED_FLAGS "-std=c++11 ${CMAKE_REQUIRED_FLAGS}")
+  set(CMAKE_REQUIRED_FLAGS "-std=c++17 ${CMAKE_REQUIRED_FLAGS}")
   CHECK_CXX_SOURCE_COMPILES("
 #include <atomic>
 #include <cstdint>