Fixes create_sdk target for cross-builds.

tools/utils.py

 # 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.
 
 # This file contains a set of utilities functions used by other Python-based
 # scripts.
 
 import commands
 import os
 import platform
@@ skipping 224 matching lines @@
   if platform.system() == 'Windows':
     gsutil = 'e:\\\\b\\build\\scripts\\slave\\gsutil'
   return gsutil
 
 def GetBuildMode(mode):
   return BUILD_MODES[mode]
 
 def GetArchFamily(arch):
   return ARCH_FAMILY[arch]
 
+def IsCrossBuild(target_os, arch):
+  host_arch = ARCH_GUESS
+  return ((GetArchFamily(host_arch) != GetArchFamily(arch)) or
+          (target_os != GuessOS()))
+
 def GetBuildConf(mode, arch, conf_os=None):
   if conf_os == 'android':
     return '%s%s%s' % (GetBuildMode(mode), conf_os.title(), arch.upper())
   else:
     # Ask for a cross build if the host and target architectures don't match.
     host_arch = ARCH_GUESS
     cross_build = ''
     if GetArchFamily(host_arch) != GetArchFamily(arch):
       print "GetBuildConf: Cross-build of %s on %s\n" % (arch, host_arch)
       cross_build = 'X'
     return '%s%s%s' % (GetBuildMode(mode), cross_build, arch.upper())
 
 def GetBuildDir(host_os, target_os):
   return BUILD_ROOT[host_os]
 
 def GetBuildRoot(host_os, mode=None, arch=None, target_os=None):
   build_root = GetBuildDir(host_os, target_os)
   if mode:
-    build_root = os.path.join(build_root, GetBuildConf(mode, arch))
+    build_root = os.path.join(build_root, GetBuildConf(mode, arch, target_os))
   return build_root
 
 def GetBaseDir():
   return BASE_DIR
 
 def GetShortVersion():
   version = ReadVersionFile()
   return ('%s.%s.%s.%s.%s' % (
       version.major, version.minor, version.patch, version.prerelease,
       version.prerelease_patch))
@@ skipping 310 matching lines @@
     os.chdir(self._working_directory)
 
   def __exit__(self, *_):
     print "Enter directory = ", self._old_cwd
     os.chdir(self._old_cwd)
 
 
 if __name__ == "__main__":
   import sys
   Main(sys.argv)