lib: only load inspector stuff if necessary

PR-URL: #20567
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

lib/internal/bootstrap/node.js

@@ -64,7 +64,10 @@
       NativeModule.require('internal/process/write-coverage').setup();
 
     NativeModule.require('internal/trace_events_async_hooks').setup();
-    NativeModule.require('internal/inspector_async_hook').setup();
+
+    if (process.config.variables.v8_enable_inspector) {
+      NativeModule.require('internal/inspector_async_hook').setup();
+    }
 
     _process.setupChannel();
     _process.setupRawDebug();