RFR(S): 8180391: move SerializationUtils to top level testlibrary

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8180391/webrev.00/index.html
> 119 lines changed: 56 ins; 54 del; 9 mod;

Hi all,

could you please review this small fix which move SerializationUtils class from jdk testlibrary to top level testlibrary? jdk.testlibrary.SerializationUtils does not have dependency on any other test library classes, so we can simply move it to the top level testlibrary and update the tests which use it.

this fix is a part of ongoing effort on merging and cleaning up our test libraries[1].

webrev: http://cr.openjdk.java.net/~iignatyev//8180391/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8180391
testing: affected tests (java/lang)

[1] https://bugs.openjdk.java.net/browse/JDK-8075327

Thanks,
-- Igor