hg: jdk10/jdk10/jdk: 8180391: move SerializationUtils to top level testlibrary

[igor.ignatyev at oracle.com]

Changeset: f6654aece3ac
Author:    iignatyev
Date:      2017-05-18 15:43 -0700
URL:       http://hg.openjdk.java.net/jdk10/jdk10/jdk/rev/f6654aece3ac

8180391: move SerializationUtils to top level testlibrary
Reviewed-by: psandoz

! test/java/lang/String/CompactString/SerializationTest.java
! test/java/lang/StringBuffer/CompactStringBufferSerialization.java
! test/java/lang/StringBuilder/CompactStringBuilderSerialization.java
- test/lib/testlibrary/jdk/testlibrary/SerializationUtils.java