Fix boringssl defines for MIPS build.

third_party/boringssl/boringssl_dart.gyp

 # Copyright 2014 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.
 
 {
   'includes': [
     '../../runtime/tools/gyp/runtime-configurations.gypi',
     'boringssl_configurations.gypi',
   ],
   'targets': [
@@ skipping 23 matching lines @@
             '<@(boringssl_mac_x86_64_sources)'
           ],
         }],
         ['OS == "linux" or OS == "android"', {
           'sources': [
             '<@(boringssl_linux_x86_64_sources)',
             '<@(boringssl_linux_x86_sources)',
             '<@(boringssl_linux_arm_sources)',
             '<@(boringssl_linux_aarch64_sources)',
           ],
+          'defines': [
+            '_BSD_SOURCE',
+            '_XOPEN_SOURCE=700',
+          ],
         }],
         ['OS == "win"', {
           'defines': [ 'OPENSSL_NO_ASM', 'WIN32_LEAN_AND_MEAN' ],
         }],
       ],
       'include_dirs': [
         'src/include',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           'src/include',
         ],
       },
     },
   ],
 }