[gn build] Port a6b846a

Author: llvmgnsyncbot

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

@@ -188,6 +188,7 @@ if (current_toolchain == default_toolchain) {
       "__algorithm/ranges_binary_search.h",
       "__algorithm/ranges_clamp.h",
       "__algorithm/ranges_contains.h",
+      "__algorithm/ranges_contains_subrange.h",
       "__algorithm/ranges_copy.h",
       "__algorithm/ranges_copy_backward.h",
       "__algorithm/ranges_copy_if.h",