RFR (s): 8026849 - Fix typos in the GC code, part 2

[Jesper Wilhelmsson]

Hi,

Could I have a couple of reviews for this small patch?

These are fixes for a couple of typos that I didn't include in the big fix 
recently pushed. They were not included since they do not reside in comments but 
rather assert messages, flag descriptions and some verbose messages.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8026849

Webrev:
http://cr.openjdk.java.net/~jwilhelm/8026849/webrev/


This patch also contains a fix for 8023899 - Typo in TraceCPUTime message.
https://bugs.openjdk.java.net/browse/JDK-8023899

Thanks,
/Jesper