[CMake] Use NOMINMAX compilation flag on Windows.

unittest/python/pybind11/CMakeLists.txt

@@ -15,5 +15,9 @@ if(CMAKE_VERSION VERSION_GREATER 3.11)
       message(STATUS "CXX_STANDARD for cpp2pybind11 set changed from ${CMAKE_CXX_STANDARD} to 14")
       set_target_properties(cpp2pybind11 PROPERTIES CXX_STANDARD 14)
     endif()
+
+    if(WIN32)
+      target_compile_definitions(cpp2pybind11 PRIVATE -DNOMINMAX)
+    endif(WIN32)
   endif()
 endif()