Exclude more files from Android build

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 173 matching lines @@
           ],
         }],
         ['OS=="android"', {
           'sources': [
             'android_native_window.cc',
             'android_native_window.h',
           ],
           'sources!': [
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.h',
+            'gl_context_osmesa.cc',
             'system_monitor_posix.cc',
           ],
           'defines': [
             'GL_GLEXT_PROTOTYPES',
             'EGL_EGLEXT_PROTOTYPES',
           ],
         }],
       ],
     },
   ],
 }