Update woff2 to 2bc6acf

third_party/woff2/BUILD.gn

 # Copyright 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.
 
-config("woff2_warnings") {
-  if (!is_win || is_clang) {
-    cflags = [ "-Wno-unused-function" ]
-  }
-}
-
 source_set("woff2_dec") {
   sources = [
     "src/buffer.h",
     "src/round.h",
     "src/store_bytes.h",
     "src/table_tags.cc",
     "src/table_tags.h",
     "src/variable_length.cc",
     "src/variable_length.h",
     "src/woff2_common.cc",
     "src/woff2_common.h",
     "src/woff2_dec.cc",
     "src/woff2_dec.h",
     "src/woff2_out.cc",
     "src/woff2_out.h",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
-  configs += [ ":woff2_warnings" ]
 
   deps = [
     "//third_party/brotli",
   ]
 
   include_dirs = [
     "src",
     "//third_party/brotli/dec",
   ]
 
   # TODO(ksakamoto): http://crbug.com/167187
   if (is_win) {
     cflags = [ "/wd4267" ]  # Conversion from size_t to 'type'.
   }
 }