Implement tracking of BUILD.gn files used to define target, toolchain or

tools/gn/functions.cc

Index: tools/gn/functions.cc
diff --git a/tools/gn/functions.cc b/tools/gn/functions.cc
index 272cd9430bc96d82fef310a8f8ef5600cd3e2725..532040490a000b4793638bb05a7db780773a92ad 100644
--- a/tools/gn/functions.cc
+++ b/tools/gn/functions.cc
@@ -337,7 +337,8 @@ Value RunConfig(const FunctionCallNode* function,
     g_scheduler->Log("Defining config", label.GetUserVisibleName(true));
 
   // Create the new config.
-  std::unique_ptr<Config> config(new Config(scope->settings(), label));
+  std::unique_ptr<Config> config(
+      new Config(scope->settings(), label, scope->input_files()));
   config->set_defined_from(function);
   if (!Visibility::FillItemVisibility(config.get(), scope, err))
     return Value();
@@ -792,7 +793,8 @@ Value RunPool(const FunctionCallNode* function,
   }
 
   // Create the new pool.
-  std::unique_ptr<Pool> pool(new Pool(scope->settings(), label));
+  std::unique_ptr<Pool> pool(
+      new Pool(scope->settings(), label, scope->input_files()));
   pool->set_depth(depth->int_value());
 
   // Save the generated item.