Roll buildtools to pull clang-format, Standard: Cpp11 in .clang-format

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of 'src').
 #
@@ skipping 37 matching lines @@
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   'swarming_revision': '79940aeeec0ace78ade0fec27515850268761af5',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
   "angle_revision": "df647a2a354d5dc9affdd6a982fccb6b95d361b0",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.
-  'buildtools_revision': '6d24aadb361dc9a914bbe321915972461fe0444c',
+  'buildtools_revision': '56bc51aff4175d3fa27dcd0faa2c345ab046c8a5',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFIum
   # and whatever else without interference from each other.
   'pdfium_revision': '7a649fe262d77f93ad3213f53e973a7665d95a23',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openmax_dl
   # and whatever else without interference from each other.
   'openmax_dl_revision': '79e64bc9243e5ff11822434cf39b9fabefff3bfb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
@@ skipping 722 matching lines @@
     # corresponding .py files have already been deleted.
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
         'python',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
   },
 ]