RFR (S) - JDK-8233075 - JFR - nmetods - misspelled in several places

[Eric Caspole]

Hi everybody,
Could I get reviews on this spelling fix to correct nmetods -> nmethods 
in JFR compiler stats. I want to to use this for something and the 
misspelling was bugging me.

This passed tier 1 and 2 on linux-x64. Let me know if there is other JFR 
testing needed.
Thanks,
Eric

JBS:
https://bugs.openjdk.java.net/browse/JDK-8233075

Webrev:
http://cr.openjdk.java.net/~ecaspole/JDK-8233075/02/webrev/