Adding in libX11, which seems to be needed for test_common on linux....

build/libs.gyp

 # Copyright (c) 2009 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,
     'dx_redist_path': '../../o3d-internal/third_party/dx_nov_2007_redist',
     'dx_redist_exists': '<!(python file_exists.py ../../o3d-internal/third_party/dx_nov_2007_redist/d3dx9_36.dll)',
   },
@@ skipping 15 matching lines @@
             'direct_dependent_settings': {
               'defines': [
                 'GL_GLEXT_PROTOTYPES',
               ],
               'scons_variable_settings': {
                 'LIBPATH': [
                   '../../<(glewdir)/lib',
                 ],
               },
               'libraries': [
-                "-lGL",
-                "-lGLEW",
+                '-lGL',
+                '-lGLEW',
+                '-lX11',
               ],
             },
           },
         ],
         [ 'OS=="mac"',
           {
             'direct_dependent_settings': {
               'libraries': [
                 '$(SDKROOT)/System/Library/Frameworks/OpenGL.framework',
               ],
@@ skipping 129 matching lines @@
       }
     ],
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: