clang build script: Clobber old Android toolchains.

tools/clang/scripts/update.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """This script is used to download prebuilt clang binaries.
 
 It is also used by package.py to build the prebuilt clang binaries."""
 
 import argparse
@@ skipping 744 matching lines @@
   if args.with_android:
     make_toolchain = os.path.join(
         ANDROID_NDK_DIR, 'build', 'tools', 'make_standalone_toolchain.py')
     for target_arch in ['aarch64', 'arm', 'i686']:
       # Make standalone Android toolchain for target_arch.
       toolchain_dir = os.path.join(
           LLVM_BUILD_DIR, 'android-toolchain-' + target_arch)
       RunCommand([
           make_toolchain,
           '--api=' + ('21' if target_arch == 'aarch64' else '19'),
+          '--force',
           '--install-dir=%s' % toolchain_dir,
           '--stl=stlport',
           '--arch=' + {
               'aarch64': 'arm64',
               'arm': 'arm',
               'i686': 'x86',
           }[target_arch]])
       # Android NDK r9d copies a broken unwind.h into the toolchain, see
       # http://crbug.com/357890
       for f in glob.glob(os.path.join(toolchain_dir, 'include/c++/*/unwind.h')):
@@ skipping 122 matching lines @@
     args.force_local_build = True
     if 'OS=android' not in os.environ.get('GYP_DEFINES', ''):
       # Only build the Android ASan rt on ToT bots when targetting Android.
       args.with_android = False
 
   return UpdateClang(args)
 
 
 if __name__ == '__main__':
   sys.exit(main())