RFR(S): 7902609: Some serializable classes in jmh-core don't have serialVersionUID

[Dmitry Chuyko]

Hello,

Please review a small fix for (again) missing serial ids in jmh-core. I 
added a warning in maven-compiler-plugin configuration and then added 
IDE-generated ids to fix all cases.

bug: https://bugs.openjdk.java.net/browse/CODETOOLS-7902609

webrev: http://cr.openjdk.java.net/~dchuyko/7902609/webrev.00/

-Dmitry