Add woff2 to src/third_party

third_party/woff2/src/port.h

+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Helper function for bit twiddling
+
+#ifndef WOFF2_PORT_H_
+#define WOFF2_PORT_H_
+
+namespace woff2 {
+
+typedef unsigned int       uint32;
+
+inline int Log2Floor(uint32 n) {
+#if defined(__GNUC__)
+  return n == 0 ? -1 : 31 ^ __builtin_clz(n);
+#else
+  if (n == 0)
+    return -1;
+  int log = 0;
+  uint32 value = n;
+  for (int i = 4; i >= 0; --i) {
+    int shift = (1 << i);
+    uint32 x = value >> shift;
+    if (x != 0) {
+      value = x;
+      log += shift;
+    }
+  }
+  assert(value == 1);
+  return log;
+#endif
+}
+
+} // namespace woff2
+#endif  // WOFF2_PORT_H_