8237182(T): Update copyright header for shenandoah and epsilon files

[Mikael Vidstedt]

Please review this small change which adjusts the copyright headers for shenandoah and epsilon related files.

JBS: https://bugs.openjdk.java.net/browse/JDK-8237182 <https://bugs.openjdk.java.net/browse/JDK-8237182>
webrev: http://cr.openjdk.java.net/~mikael/webrevs/8237182/webrev.00/open/webrev/ <http://cr.openjdk.java.net/~mikael/webrevs/8237182/webrev.00/open/webrev/>

Description:

Many/most of the shenandoah and epsilon related files are missing the following line in the copyright header: 

"DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.”

This change simply adds that line to the relevant files. In src/hotspot/share/gc/shenandoah/shenandoahNormalMode.cpp there was also a missing empty line before one of the paragraphs in the header.

Cheers,
Mikael