MSVS: Normalize paths against gyp directory.

test/msvs/filters/subdir/subdir.gyp

Index: test/msvs/filters/subdir/subdir.gyp
diff --git a/test/build-option/hello.gyp b/test/msvs/filters/subdir/subdir.gyp
similarity index 53%
copy from test/build-option/hello.gyp
copy to test/msvs/filters/subdir/subdir.gyp
index 1974d51ccd1934cfc0841f26e7118448b2fb1c98..b93dc9117fda2f06e2201ec99bd15ba86d36d006 100644
--- a/test/build-option/hello.gyp
+++ b/test/msvs/filters/subdir/subdir.gyp
@@ -1,15 +1,16 @@
-# Copyright (c) 2009 Google Inc. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-{
-  'targets': [
-    {
-      'target_name': 'hello',
-      'type': 'executable',
-      'sources': [
-        'hello.c',
-      ],
-    },
-  ],
-}
+# Copyright (c) 2015 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'targets': [
+    {
+      'target_name': 'normalize',
+      'type': 'executable',
+      'sources': [
+        '../subdir/folder1/a.c',
+        '../subdir/folder2/b.c',
+      ],
+    },
+  ],
+}