fix: Add MSVC flag

	-	Previously, The MSVC version was not well recognized
		--> Hence, there was some bugy macro specific to MSVC/c++20
	-	This Commit resolve the issue and I am now able to
			compile the problematic testcase
	-	Question : SHould we add this flag not at the tets level
			but at the main CMakeFiles level ?

Author: sbstndb

test/CMakeLists.txt

@@ -74,7 +74,7 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR (CMAKE_CXX_COMPILER_ID MATCHES "Intel"
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -DSKIP_ON_WERROR")
   endif()
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_cxx_std_flag} /MP /bigobj")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_cxx_std_flag} /Zc:__cplusplus /MP /bigobj")
   set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /MANIFEST:NO")
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
   add_definitions(-D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING)