*.{c,cc,h}: normalize AOMedia copyright

Use a consistent copyright line and update instances of a WebM copyright
body to contain the AOMedia one.

Bug: aomedia:3525
Change-Id: Icb2e5d228850a9ab81eb695d7abfcadeaca29481
diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index d256512..759a95c 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, Alliance for Open Media. All rights reserved
+ * Copyright (c) 2016, Alliance for Open Media. All rights reserved.
  *
  * This source code is subject to the terms of the BSD 2 Clause License and
  * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License