[iOS/Mac/GN] Update timestamp when copying a tree.

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 7807746f146f7dbeb49640e1c11fa912a0b3e95a..7b487380532dbfe48c6bb87be057b97d6f08ce65 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -283,7 +283,8 @@ template("mac_toolchain") {
       }
       _tool = rebase_path("//build/toolchain/mac/copy_bundle_data.py",
                           root_build_dir)
-      command = "python $_tool ${_extra_args} {{source}} {{output}}"
+      command = "python $_tool --version-for-gn=1 " +
+                "${_extra_args} {{source}} {{output}}"
       description = "COPY_BUNDLE_DATA {{source}} {{output}}"
       pool = ":bundle_pool($default_toolchain)"
     }
@@ -297,9 +298,8 @@ template("mac_toolchain") {
         _sdk_name = mac_sdk_name
         _min_deployment_target = mac_deployment_target
       }
-      command = "rm -f {{output}} && " +
-                "python $_tool -p $_sdk_name -t $_min_deployment_target " +
-                "-o {{output}} {{inputs}}"
+      command = "python $_tool --version-for-gn=1 -p $_sdk_name " +
+                "-t $_min_deployment_target -o {{output}} {{inputs}}"
 
       description = "COMPILE_XCASSETS {{output}}"
       pool = ":bundle_pool($default_toolchain)"