Use gyp targets to link in X11 libraries instead of setting -lXfoo

ui/gl/gl.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
 
   'targets': [
@@ skipping 195 matching lines @@
             'defines': [
               'GL_GLEXT_PROTOTYPES',
             ],
           },
           'link_settings': {
             'libraries': [
               '-lX11',
               '-lXcomposite',
             ],
           },
+          'dependencies': [
+            '<(DEPTH)/build/linux/system.gyp:x11',
+            '<(DEPTH)/build/linux/system.gyp:xcomposite',
+            '<(DEPTH)/build/linux/system.gyp:xext',
+          ],
         }],
         ['OS=="win"', {
           'sources': [
             'gl_context_wgl.cc',
             'gl_context_wgl.h',
             'gl_egl_api_implementation.cc',
             'gl_egl_api_implementation.h',
             'gl_surface_wgl.cc',
             'gl_surface_wgl.h',
             'gl_wgl_api_implementation.cc',
@@ skipping 123 matching lines @@
           'variables': {
             'jni_gen_package': 'ui/gl',
             'jni_generator_ptr_type': 'long',
           },
           'includes': [ '../../build/jni_generator.gypi' ],
         },
       ],
     }],
   ],
 }