Update C++ standard to 17 (#2973)

Summary:
Following the change in PyTorch core.

https://github.com/pytorch/pytorch/commit/87e4a087784c805312a2b48bb063d2400df26c5e

Pull Request resolved: https://github.com/pytorch/audio/pull/2973

Reviewed By: xiaohui-zhang

Differential Revision: D42462709

Pulled By: mthrok

fbshipit-source-id: 60c2aa3d63fe25d8e0b7aa476404e7a55d6eb87f

CMakeLists.txt

@@ -24,19 +24,10 @@ string(FIND "${CMAKE_CXX_FLAGS}" "-std=c++" env_cxx_standard)
 if(env_cxx_standard GREATER -1)
   message(
       WARNING "C++ standard version definition detected in environment variable."
-      "PyTorch requires -std=c++14. Please remove -std=c++ settings in your environment.")
+      "PyTorch requires -std=c++17. Please remove -std=c++ settings in your environment.")
 endif()
-
-set(CMAKE_CXX_STANDARD 14)
-set(CMAKE_C_STANDARD 11)
-
-# https://developercommunity.visualstudio.com/t/VS-16100-isnt-compatible-with-CUDA-11/1433342
-if(MSVC)
-  if(USE_CUDA)
-    set(CMAKE_CXX_STANDARD 17)
-  endif()
-endif()
-
+set(CMAKE_CXX_STANDARD 17 CACHE STRING "The C++ standard whose features are requested to build this target.")
+set(CMAKE_C_STANDARD   11 CACHE STRING "The C standard whose features are requested to build this target.")
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)