Remove more feature in product mode

runtime/vm/thread_interrupter_macos.cc

Index: runtime/vm/thread_interrupter_macos.cc
diff --git a/runtime/vm/thread_interrupter_macos.cc b/runtime/vm/thread_interrupter_macos.cc
index a25c3c2048ead7c479288d21d063998b680706bd..e46dbc7d2a77f19d82e3d873d4d75169e975915b 100644
--- a/runtime/vm/thread_interrupter_macos.cc
+++ b/runtime/vm/thread_interrupter_macos.cc
@@ -15,6 +15,8 @@
 
 namespace dart {
 
+#ifndef PRODUCT
+
 DECLARE_FLAG(bool, thread_interrupter);
 DECLARE_FLAG(bool, trace_thread_interrupter);
 
@@ -61,6 +63,8 @@ void ThreadInterrupter::RemoveSignalHandler() {
   SignalHandler::Remove();
 }
 
+#endif  // !PRODUCT
+
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)