RFR: 8231671: Fix copyright headers in hotspot (missing comma after year)

[Leo Korinth]

Hi,

Please review these fixes to copyright headers (comma is added).

This is tiresome. I have asked Yoshiki Sato to file a fix for jcheck, so 
that we do not have to do this in the future.

Webrev:
http://cr.openjdk.java.net/~lkorinth/8231671/00

Bug:
https://bugs.openjdk.java.net/browse/JDK-8231671

Testing:
None.

Thanks,
Leo