Fix untrusted.gypi and build_nexe.py

build/untrusted.gypi

 # Copyright (c) 2011 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': {
     'variables': {
       # Enable -Werror by default, but put it in a variable so it can
       # be optionally disabled.
       'werror%': '-Werror',
       # 1 to use goma.
       'use_goma%': 0,
     },
     # Default C compiler defines.
     'nacl_default_defines': [
-      '__linux__',
       '__STDC_LIMIT_MACROS=1',
       '__STDC_FORMAT_MACROS=1',
       '_GNU_SOURCE=1',
       '_BSD_SOURCE=1',
       '_POSIX_C_SOURCE=199506',
       '_XOPEN_SOURCE=600',
       'DYNAMIC_ANNOTATIONS_ENABLED=1',
       'DYNAMIC_ANNOTATIONS_PREFIX=NACL_',
     ],
     'nacl_default_compile_flags': [
@@ skipping 1722 matching lines @@
                 ],
               },
             ],
           }],
         ],
       }], # end MIPS
       # end pnacl actions for building ABI-biased native libraries
     ], # end conditions for pnacl biased nlib
   },
 }