[zircon][build][kazoo] Add source_name_part to host_tool_action template

In host_tool_action_foreach, all invocations were using the same .d file
named only by target_name (which works file for host_tool_action).

So on subsequent runs, ninja would determine that the wrong output was
named in the .d file and so mark (one of the other) files as dirty.

Bug: 37505
Bug: 38488
Bug: 36581
Change-Id: Ia5830a6d935d6f70726e2b37c69a6f8319f8414e
diff --git a/zircon/public/gn/host_tool_action.gni b/zircon/public/gn/host_tool_action.gni
index fe378b9..b80dfe3 100644
--- a/zircon/public/gn/host_tool_action.gni
+++ b/zircon/public/gn/host_tool_action.gni
@@ -93,7 +93,8 @@
     ]
     inputs += [ rspfile ]
 
-    depfile = "$target_out_dir/$target_name._host_tool_action.d"
+    depfile =
+        "$target_out_dir/$target_name.{{source_file_part}}._host_tool_action.d"
     if (defined(invoker.depfile)) {
       orig_depfile = rebase_path(invoker.depfile, root_build_dir)
     } else {