Use /std:c++14 with MSVC.

 * Per tqchen: project has already moved to C++14
 * Presubmit failed for code that built locally on gcc.

CMakeLists.txt

@@ -304,12 +304,15 @@ include(cmake/modules/contrib/TFLite.cmake)
 include(cmake/modules/contrib/TF_TVMDSOOP.cmake)
 include(cmake/modules/contrib/CoreML.cmake)
 
+include(CheckCXXCompilerFlag)
 if(NOT MSVC)
-  include(CheckCXXCompilerFlag)
   check_cxx_compiler_flag("-std=c++14" SUPPORT_CXX14)
-  message(STATUS "Build with c++14")
   set(CMAKE_CXX_FLAGS "-std=c++14 ${CMAKE_CXX_FLAGS}")
   set(CMAKE_CUDA_STANDARD 14)
+else()
+  check_cxx_compiler_flag("/std:c++14" SUPPORT_CXX14)
+  set(CMAKE_CXX_FLAGS "/std:c++14 ${CMAKE_CXX_FLAGS}")
+  set(CMAKE_CUDA_STANDARD 14)
 endif()
 
 add_library(tvm SHARED ${COMPILER_SRCS} ${RUNTIME_SRCS})