[7u6] Request for approval: 7156963 Incorrect copyright header in java/io/SerialCallbackContext

[Seán Coffey]

To keep things consistent across 7u/8 we should also port this simple 
copyright change to jdk7u.

Changes same as JDK 8 changeset :  
http://hg.openjdk.java.net/jdk8/tl/jdk/rev/00c9d6cce3ec


Regards,
Sean.