VM: Separate precompilation-specific code, make flags const.

runtime/bin/bin.gypi

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 {
   'variables': {
     'gen_source_dir': '<(SHARED_INTERMEDIATE_DIR)',
 
     'io_cc_file': '<(gen_source_dir)/io_gen.cc',
     'io_patch_cc_file': '<(gen_source_dir)/io_patch_gen.cc',
@@ skipping 734 matching lines @@
         'builtin_natives.cc',
         'builtin_nolib.cc',
         'builtin.h',
         'io_natives.h',
         'vmservice_impl.cc',
         'vmservice_impl.h',
         'snapshot_empty.cc',
         '<(resources_cc_file)',
         '<(observatory_assets_cc_file)',
       ],
+      'defines': [
+        'DART_PRECOMPILED_RUNTIME',
+      ],
       'conditions': [
         ['OS=="win"', {
           'link_settings': {
             'libraries': [ '-lws2_32.lib', '-lRpcrt4.lib', '-lwinmm.lib' ],
           },
           # Generate an import library on Windows, by exporting a function.
           # Extensions use this import library to link to the API in dart.exe.
           'msvs_settings': {
             'VCLinkerTool': {
               'AdditionalOptions': [ '/EXPORT:Dart_True' ],
@@ skipping 227 matching lines @@
         }],
         ['OS=="linux"', {
           'cflags': [
             '-fPIC',
           ],
         }],
       ],
     },
   ],
 }