add system libXNVCtrl library support in linux unbundle

build/linux/unbundle/libXNVCtrl.gyp

-# Copyright 2013 The Chromium Authors. All rights reserved.
+# Copyright (c) 2013 The Chromium Authors. 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': 'libpng',
+      'target_name': 'libXNVCtrl',
       'type': 'none',
-      'dependencies': [
-        '../zlib/zlib.gyp:zlib',
-      ],
-      'direct_dependent_settings': {
-        'cflags': [
-          '<!@(pkg-config --cflags libpng)',
-        ],
-      },
-      'link_settings': {
-        'ldflags': [
-          '<!@(pkg-config --libs-only-L --libs-only-other libpng)',
-        ],
-        'libraries': [
-          '<!@(pkg-config --libs-only-l libpng)',
-        ],
-      },
       'variables': {
         'headers_root_path': '.',
         'header_filenames': [
-          'png.h',
-          'pngconf.h',
+          'NVCtrlLib.h',
+          'NVCtrl.h',
         ],
       },
       'includes': [
         '../../build/shim_headers.gypi',
       ],
-    },
+      'direct_dependent_settings': {
+        'cflags': [
+            '<!@(pkg-config --cflags libXNVCtrl)',
+        ],
+      },
+      'link_settings': {
+        'ldflags': [
+          '<!@(pkg-config --libs-only-L --libs-only-other libXNVCtrl)',
+        ],
+        'libraries': [
+          '<!@(pkg-config --libs-only-l libXNVCtrl)',
+        ],
+      },
+    }
   ],
 }