[gn] Move build to gypfiles

build/gyp_environment.py

-# Copyright 2015 the V8 project authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""
-Sets up various automatic gyp environment variables. These are used by
-gyp_v8 and landmines.py which run at different stages of runhooks. To
-make sure settings are consistent between them, all setup should happen here.
-"""
-
-import os
-import sys
-import vs_toolchain
-
-SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
-V8_ROOT = os.path.abspath(os.path.join(SCRIPT_DIR, os.pardir))
-
-
-def apply_gyp_environment(file_path=None):
-  """
-  Reads in a *.gyp_env file and applies the valid keys to os.environ.
-  """
-  if not file_path or not os.path.exists(file_path):
-    return
-  file_contents = open(file_path).read()
-  try:
-    file_data = eval(file_contents, {'__builtins__': None}, None)
-  except SyntaxError, e:
-    e.filename = os.path.abspath(file_path)
-    raise
-  supported_vars = ( 'V8_GYP_FILE',
-                     'V8_GYP_SYNTAX_CHECK',
-                     'GYP_DEFINES',
-                     'GYP_GENERATOR_FLAGS',
-                     'GYP_GENERATOR_OUTPUT', )
-  for var in supported_vars:
-    val = file_data.get(var)
-    if val:
-      if var in os.environ:
-        print 'INFO: Environment value for "%s" overrides value in %s.' % (
-            var, os.path.abspath(file_path)
-        )
-      else:
-        os.environ[var] = val
-
-
-def set_environment():
-  """Sets defaults for GYP_* variables."""
-
-  if 'SKIP_V8_GYP_ENV' not in os.environ:
-    # Update the environment based on v8.gyp_env
-    gyp_env_path = os.path.join(os.path.dirname(V8_ROOT), 'v8.gyp_env')
-    apply_gyp_environment(gyp_env_path)
-    vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()