[gn build] Port 34e0f9c

Author: llvmgnsyncbot

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

@@ -575,7 +575,6 @@ if (current_toolchain == default_toolchain) {
       "__locale_dir/locale_base_api/ibm.h",
       "__locale_dir/locale_base_api/musl.h",
       "__locale_dir/locale_base_api/openbsd.h",
-      "__locale_dir/locale_guard.h",
       "__locale_dir/pad_and_output.h",
       "__locale_dir/support/apple.h",
       "__locale_dir/support/bsd_like.h",