Add missing C file.

library/src/main/java/com/google/android/exoplayer/C.java

+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * 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.
+ */
+package com.google.android.exoplayer;
+
+/**
+ * Defines constants that are generally useful throughout the library.
+ */
+public final class C {
+
+  /**
+   * Represents an unbounded length of data.
+   */
+  public static final int LENGTH_UNBOUNDED = -1;
+
+  private C() {}
+
+}