node: warn if cwd is inaccessible during bootstrap

Author: Fishrock123

lib/internal/bootstrap_node.js

@@ -374,6 +374,9 @@
       threw = false;
     } finally {
       if (threw) {
+        process.emitWarning('The current working directory was inaccessible.' +
+                            '\nFalling back to the executable\'s directory.',
+                            'BootstrapInaccessibleCwdWarning');
         // getcwd(3) can fail if the current working directory has been deleted.
         // Fall back to the directory name of the (absolute) executable path.
         // It's not really correct but what are the alternatives?