Add netbsd support to gyp build.

src/d8.gyp

 # Copyright 2010 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 46 matching lines @@
               ],
             }, {
               'dependencies': [
                 'd8_js2c',
               ],
             }],
             [ 'console=="readline"', {
               'libraries': [ '-lreadline', ],
               'sources': [ 'd8-readline.cc' ],
             }],
-            [ '(OS=="linux" or OS=="mac" or OS=="freebsd" \
-              or OS=="openbsd" or OS=="solaris" or OS=="android")', {
+            ['(OS=="linux" or OS=="mac" or OS=="freebsd" or OS=="netbsd" \
+               or OS=="openbsd" or OS=="solaris" or OS=="android")', {
               'sources': [ 'd8-posix.cc', ]
             }],
             [ 'OS=="win"', {
               'sources': [ 'd8-windows.cc', ]
             }],
           ],
         }],
       ],
     },
     {
@@ skipping 28 matching lines @@
             '<@(_outputs)',
             'D8',
             'off',  # compress startup data
             '<@(js_files)'
           ],
         },
       ],
     }
   ],
 }