Clang package.py: fix list append vs. extend mistake

tools/clang/scripts/package.py

 #!/usr/bin/env python
 # Copyright (c) 2015 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 will check out llvm and clang, and then package the results up
 to a tgz file."""
 
 import argparse
 import fnmatch
@@ skipping 81 matching lines @@
 
     # Do a clobber build.
     shutil.rmtree(LLVM_BOOTSTRAP_DIR, ignore_errors=True)
     shutil.rmtree(LLVM_BOOTSTRAP_INSTALL_DIR, ignore_errors=True)
     shutil.rmtree(LLVM_BUILD_DIR, ignore_errors=True)
 
     build_cmd = [sys.executable, os.path.join(THIS_DIR, 'update.py'),
                  '--bootstrap', '--force-local-build', '--run-tests',
                  '--no-stdin-hack']
     if args.gcc_toolchain is not None:
-      build_cmd.append(['--gcc-toolchain', args.gcc_toolchain])
+      build_cmd.extend(['--gcc-toolchain', args.gcc_toolchain])
     TeeCmd(build_cmd, log)
 
   stamp = open(STAMP_FILE).read().rstrip()
   pdir = 'clang-' + stamp
   print pdir
   shutil.rmtree(pdir, ignore_errors=True)
 
   # Copy a whitelist of files to the directory we're going to tar up.
   # This supports the same patterns that the fnmatch module understands.
   so_ext = 'dylib' if sys.platform == 'darwin' else 'so'
@@ skipping 94 matching lines @@
               filter=PrintTarProgress)
     print ('gsutil cp -a public-read %s.tgz '
            'gs://chromium-browser-clang/%s/%s.tgz') % (golddir, platform,
                                                        golddir)
 
   # FIXME: Warn if the file already exists on the server.
 
 
 if __name__ == '__main__':
   sys.exit(main())