mac: Turn on -Wunused-functions.

tools/gn/target.cc

Index: tools/gn/target.cc
diff --git a/tools/gn/target.cc b/tools/gn/target.cc
index b12d284e957880ab33a2266b868fa358c6b60160..635c50eac1ea223a543e67b219d895264bd45ddd 100644
--- a/tools/gn/target.cc
+++ b/tools/gn/target.cc
@@ -12,11 +12,6 @@ namespace {
 
 typedef std::set<const Config*> ConfigSet;
 
-void TargetResolvedThunk(const base::Callback<void(const Target*)>& cb,
-                         const Target* t) {
-  cb.Run(t);
-}
-
 // Merges the dependent configs from the given target to the given config list.
 // The unique_configs list is used for de-duping so values already added will
 // not be added again.