Fix GN hang spawning a process.

tools/gn/function_exec_script.cc

Index: tools/gn/function_exec_script.cc
diff --git a/tools/gn/function_exec_script.cc b/tools/gn/function_exec_script.cc
index 56143eab7a870ec71f0872f37ee7aab944e3bcdf..572d99786afff75ce75a00444bcb61809e198b9b 100644
--- a/tools/gn/function_exec_script.cc
+++ b/tools/gn/function_exec_script.cc
@@ -187,8 +187,8 @@ bool ExecProcess(const CommandLine& cmdline,
         // Adding another element here? Remeber to increase the argument to
         // reserve(), above.
 
-        std::copy(fd_shuffle1.begin(), fd_shuffle1.end(),
-                  std::back_inserter(fd_shuffle2));
+        for (size_t i = 0; i < fd_shuffle1.size(); ++i)
+          fd_shuffle2.push_back(fd_shuffle1[i]);
 
         if (!ShuffleFileDescriptors(&fd_shuffle1))
           _exit(127);