Update copyright headers.

- Add copyright headers to files that did not already have them
- Update the year to the last year the file was modified in files with
  existing headers.

wa/instruments/poller/poller.c

@@ -1,3 +1,18 @@
+/*    Copyright 2018 ARM Limited
+ *
+ * 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.
+*/
+
 #include <fcntl.h>
 #include <stdio.h>
 #include <sys/poll.h>