[libcxx] [test] Add _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to msvc_stdlib_force_include.hpp.

This macro will instruct MSVC's STL to not warn about features that are deprecated in C++17,
as libcxx tests those features and uses them elsewhere.

llvm-svn: 304765

libcxx/test/support/msvc_stdlib_force_include.hpp

@@ -81,6 +81,9 @@ const AssertionDialogAvoider assertion_dialog_avoider{};
 
     // Silence warnings about raw pointers and other unchecked iterators.
     #define _SCL_SECURE_NO_WARNINGS
+
+    // Silence warnings about features that are deprecated in C++17.
+    #define _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS
 #endif // _LIBCXX_IN_DEVCRT
 
 #include <ciso646>