GN: Add an option to build against the Debian wheezy sysroot

tools/gn.py

 #!/usr/bin/env python
 # Copyright 2016 The Dart 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.
 
 import argparse
 import multiprocessing
 import os
 import subprocess
 import sys
@@ skipping 95 matching lines @@
   has_clang = (host_os != 'win'
                and args.os not in ['android']
                and not (gn_args['target_os'] == 'linux' and
                         gn_args['host_cpu'] == 'x86')
                and not gn_args['target_cpu'].startswith('arm')
                and not gn_args['target_cpu'].startswith('mips'))
   gn_args['is_clang'] = args.clang and has_clang
 
   gn_args['is_asan'] = args.asan and gn_args['is_clang']
 
-  if args.target_sysroot:
-    gn_args['target_sysroot'] = args.target_sysroot
+  # Setup the user-defined sysroot.
+  if gn_args['target_os'] == 'linux' and args.wheezy:
+    gn_args['dart_use_wheezy_sysroot'] = True
+  else:
+    if args.target_sysroot:
+      gn_args['target_sysroot'] = args.target_sysroot
 
-  if args.toolchain_prefix:
-    gn_args['toolchain_prefix'] = args.toolchain_prefix
+    if args.toolchain_prefix:
+      gn_args['toolchain_prefix'] = args.toolchain_prefix
 
   goma_dir = os.environ.get('GOMA_DIR')
   goma_home_dir = os.path.join(os.getenv('HOME', ''), 'goma')
   if args.goma and goma_dir:
     gn_args['use_goma'] = True
     gn_args['goma_dir'] = goma_dir
   elif args.goma and os.path.exists(goma_home_dir):
     gn_args['use_goma'] = True
     gn_args['goma_dir'] = goma_home_dir
   else:
@@ skipping 59 matching lines @@
   if host_os.startswith('win'):
     return '--ide=vs'
   elif host_os.startswith('mac'):
     return '--ide=xcode'
   else:
     return '--ide=json'
 
 
 # Environment variables for default settings.
 DART_USE_ASAN = "DART_USE_ASAN"
-
+DART_USE_WHEEZY = "DART_USE_WHEEZY"
 
 def use_asan():
   return DART_USE_ASAN in os.environ
 
 
+def use_wheezy():
+  return DART_USE_WHEEZY in os.environ
+
+
 def parse_args(args):
   args = args[1:]
   parser = argparse.ArgumentParser(description='A script to run `gn gen`.')
 
   parser.add_argument("-v", "--verbose",
       help='Verbose output.',
       default=False, action="store_true")
   parser.add_argument('--mode', '-m',
       type=str,
       help='Build variants (comma-separated).',
@@ skipping 11 matching lines @@
               'simmips,mips,simarm64,arm64,simdbc,armsimdbc]',
       default='x64')
   parser.add_argument('--asan',
       help='Build with ASAN',
       default=use_asan(),
       action='store_true')
   parser.add_argument('--no-asan',
       help='Disable ASAN',
       dest='asan',
       action='store_false')
+  parser.add_argument('--wheezy',
+      help='Use the Debian wheezy sysroot on Linux',
+      default=use_wheezy(),
+      action='store_true')
+  parser.add_argument('--no-wheezy',
+      help='Disable the Debian wheezy sysroot on Linux',
+      dest='wheezy',
+      action='store_false')
   parser.add_argument('--goma',
       help='Use goma',
       default=True,
       action='store_true')
   parser.add_argument('--no-goma',
       help='Disable goma',
       dest='goma',
       action='store_false')
   parser.add_argument('--clang',
       help='Use Clang',
@@ skipping 77 matching lines @@
       return 1
 
   endtime = time.time()
   if args.verbose:
     print ("GN Time: %.3f seconds" % (endtime - starttime))
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))