Clang: Enable c++14 dialect flag with Clang 3.5.

Modules/Compiler/Clang-CXX.cmake

@@ -23,7 +23,10 @@ elseif(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 2.1)
   set(CMAKE_CXX11_EXTENSION_COMPILE_OPTION "-std=gnu++0x")
 endif()
 
-if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
+if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.5)
+  set(CMAKE_CXX14_STANDARD_COMPILE_OPTION "-std=c++14")
+  set(CMAKE_CXX14_EXTENSION_COMPILE_OPTION "-std=gnu++14")
+elseif(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
   set(CMAKE_CXX14_STANDARD_COMPILE_OPTION "-std=c++1y")
   set(CMAKE_CXX14_EXTENSION_COMPILE_OPTION "-std=gnu++1y")
 endif()