[gn build] Port 4bc6499

Author: llvmgnsyncbot

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

@@ -671,7 +671,6 @@ if (current_toolchain == default_toolchain) {
       "__thread/timed_backoff_policy.h",
       "__threading_support",
       "__tree",
-      "__tuple/apply_cv.h",
       "__tuple/make_tuple_types.h",
       "__tuple/pair_like.h",
       "__tuple/sfinae_helpers.h",