tools: fix indentation in required-modules.js

In preparation for applying the more strict indentation linting
available in ESLint 4.0.0, correct minor indentation issues in
tools/eslint-rules/required-modules.js.

This is the only file with indentation that does not conform to the
stricter checks.

PR-URL: nodejs#13758
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Author: Trott

tools/eslint-rules/required-modules.js

@@ -77,13 +77,13 @@ module.exports = function(context) {
           function(module) {
             return foundModules.indexOf(module === -1);
           }
-          );
+        );
         missingModules.forEach(function(moduleName) {
           context.report(
             node,
             'Mandatory module "{{moduleName}}" must be loaded.',
             { moduleName: moduleName }
-            );
+          );
         });
       }
     }