hg: jigsaw/jake/langtools: Bump jtreg requiredVersion to 4.2

[mandy.chung at oracle.com]

Changeset: 9dd59ecda4eb
Author:    mchung
Date:      2016-03-15 12:01 -0700
URL:       http://hg.openjdk.java.net/jigsaw/jake/langtools/rev/9dd59ecda4eb

Bump jtreg requiredVersion to 4.2

! test/TEST.ROOT