Ignore native module tests on Windows debug build

This resolves #2558. There are no more errors when running test.py on
the debug build in Windows. When running the release build the tests
will be executed as usual.

spec/modules-spec.coffee

@@ -7,16 +7,20 @@ describe 'third-party module', ->
   fixtures = path.join __dirname, 'fixtures'
   temp.track()
 
-  describe 'runas', ->
-    it 'can be required in renderer', ->
-      require 'runas'
+  # If the test is executed with the debug build on Windows, we will skip it
+  # because native modules don't work with the debug build (see issue #2558).
+  if process.platform isnt 'win32' or
+      process.execPath.toLowerCase().indexOf('\\out\\d\\') is -1
+    describe 'runas', ->
+      it 'can be required in renderer', ->
+        require 'runas'
 
-    it 'can be required in node binary', (done) ->
-      runas = path.join fixtures, 'module', 'runas.js'
-      child = require('child_process').fork runas
-      child.on 'message', (msg) ->
-        assert.equal msg, 'ok'
-        done()
+      it 'can be required in node binary', (done) ->
+        runas = path.join fixtures, 'module', 'runas.js'
+        child = require('child_process').fork runas
+        child.on 'message', (msg) ->
+          assert.equal msg, 'ok'
+          done()
 
   describe 'q', ->
     Q = require 'q'