[gn build] Port 5d7f346

Author: llvmgnsyncbot

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

@@ -170,6 +170,7 @@ if (current_toolchain == default_toolchain) {
       "__algorithm/pstl_merge.h",
       "__algorithm/pstl_move.h",
       "__algorithm/pstl_replace.h",
+      "__algorithm/pstl_rotate_copy.h",
       "__algorithm/pstl_sort.h",
       "__algorithm/pstl_stable_sort.h",
       "__algorithm/pstl_transform.h",