[gn build] Port e53c461

Author: llvmgnsyncbot

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

@@ -429,6 +429,7 @@ if (current_toolchain == default_toolchain) {
       "__ranges/enable_view.h",
       "__ranges/iota_view.h",
       "__ranges/join_view.h",
+      "__ranges/lazy_split_view.h",
       "__ranges/non_propagating_cache.h",
       "__ranges/owning_view.h",
       "__ranges/range_adaptor.h",