module: fix regression in require ../

Fixes regression in require system that prevented loading relative
packages via main property in package.json where the file is not
index.{ext}. The regression was introduced in
cfc1272.

lib/module.js

@@ -186,6 +186,10 @@ Module._findPath = function(request, paths) {
       }
     }
 
+    if (!filename) {
+      filename = tryPackage(basePath, exts);
+    }
+
     if (!filename) {
       // try it with each of the extensions at "index"
       filename = tryExtensions(path.resolve(basePath, 'index'), exts);

test/fixtures/require-bin/bin/req.js

@@ -0,0 +1 @@
+module.exports = require('../');

test/fixtures/require-bin/lib/req.js

@@ -0,0 +1 @@
+module.exports = '';

test/fixtures/require-bin/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "req",
+  "main": "./lib/req.js"
+}

test/simple/test-require-extensions-main.js

@@ -0,0 +1,4 @@
+var common = require('../common');
+var assert = require('assert');
+
+require(common.fixturesDir + '/require-bin/bin/req.js');