Add MB configs for ClangToTLinux* bots on FYI

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 781 matching lines @@
                       help='first build clang with CC, then with itself.')
   parser.add_argument('--if-needed', action='store_true',
                       help="run only if the script thinks clang is needed")
   parser.add_argument('--force-local-build', action='store_true',
                       help="don't try to download prebuild binaries")
   parser.add_argument('--gcc-toolchain', help='set the version for which gcc '
                       'version be used for building; --gcc-toolchain=/opt/foo '
                       'picks /opt/foo/bin/gcc')
   parser.add_argument('--lto-gold-plugin', action='store_true',
                       help='build LLVM Gold plugin with LTO')
+  parser.add_argument('--llvm-force-head-revision', action='store_true',
+                      help=('use the revision in the repo when printing '
+                            'the revision'))
   parser.add_argument('--print-revision', action='store_true',
                       help='print current clang revision and exit.')
   parser.add_argument('--print-clang-version', action='store_true',
                       help='print current clang version (e.g. x.y.z) and exit.')
   parser.add_argument('--run-tests', action='store_true',
                       help='run tests after building; only for local builds')
   parser.add_argument('--tools', nargs='*',
                       help='select which chrome tools to build',
                       default=['plugins', 'blink_gc_plugin'])
   parser.add_argument('--without-android', action='store_false',
@@ skipping 23 matching lines @@
     if os.path.isdir(LLVM_BUILD_DIR):
       is_clang_required = True
     if not is_clang_required:
       return 0
     if re.search(r'\b(make_clang_dir)=', os.environ.get('GYP_DEFINES', '')):
       print 'Skipping Clang update (make_clang_dir= was set in GYP_DEFINES).'
       return 0
 
   global CLANG_REVISION, PACKAGE_VERSION
   if args.print_revision:
-    if use_head_revision:
+    if use_head_revision or args.llvm_force_head_revision:
       print GetSvnRevision(LLVM_DIR)
     else:
       print PACKAGE_VERSION
     return 0
 
   if args.print_clang_version:
     sys.stdout.write(VERSION)
     return 0
 
   # Don't buffer stdout, so that print statements are immediately flushed.
@@ skipping 10 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())