build: Remove unneeded C++11 flag in libatomic test (#1191)

The required C++ is 17 anyway.

diff --git a/cmake/StdAtomic.cmake b/cmake/StdAtomic.cmake
index 8cebe515709f3ac00eb8430bd36db12c07a4052a..119518a843e63cc5053726dd04dc117b5699a0e2 100644 (file)
--- a/cmake/StdAtomic.cmake
+++ b/cmake/StdAtomic.cmake
@@ -2,7 +2,6 @@
 
 include(CheckCXXSourceCompiles)
 
-set(CMAKE_REQUIRED_FLAGS ${CMAKE_CXX11_STANDARD_COMPILE_OPTION})
 set(
   check_std_atomic_source_code
   [=[
@@ -28,5 +27,3 @@ if(NOT std_atomic_without_libatomic)
     target_link_libraries(standard_settings INTERFACE atomic)
   endif()
 endif()
-
-set(CMAKE_REQUIRED_FLAGS)