[gn build] Port 205557c

Author: llvmgnsyncbot

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

@@ -121,6 +121,7 @@ if (current_toolchain == default_toolchain) {
       "__algorithm/pop_heap.h",
       "__algorithm/prev_permutation.h",
       "__algorithm/push_heap.h",
+      "__algorithm/ranges_max_element.h",
       "__algorithm/ranges_min_element.h",
       "__algorithm/ranges_swap_ranges.h",
       "__algorithm/remove.h",