CMake updated to require clients use C++11

CMakeLists.txt

@@ -72,6 +72,8 @@ target_include_directories(${PROJECT_NAME} PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/DirectXMesh>
   $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
 
+target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_11)
+
 if ((${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.16") AND (NOT MINGW))
     target_precompile_headers(${PROJECT_NAME} PRIVATE DirectXMesh/DirectXMeshP.h)
 endif()