[gn] port 64d413e (hardening mode)

Author: nico

llvm/utils/gn/secondary/libcxx/include/BUILD.gn

@@ -35,9 +35,7 @@ if (current_toolchain == default_toolchain) {
       "_LIBCPP_HAS_NO_WIDE_CHARACTERS=",
       "_LIBCPP_HAS_NO_STD_MODULES=",
       "_LIBCPP_ABI_DEFINES=",
-      "_LIBCPP_ENABLE_DEBUG_MODE_DEFAULT=",
-      "_LIBCPP_ENABLE_HARDENED_MODE_DEFAULT=",
-      "_LIBCPP_ENABLE_SAFE_MODE_DEFAULT=",
+      "_LIBCPP_HARDENING_MODE_DEFAULT=none",
       "_LIBCPP_PSTL_CPU_BACKEND_LIBDISPATCH=",
       "_LIBCPP_PSTL_CPU_BACKEND_SERIAL=1",
       "_LIBCPP_PSTL_CPU_BACKEND_THREAD=",