hg: jigsaw/jake/jdk: Exclude indy string concat tests until it's enabled

[mandy . chung]

Changeset: 54d2387b00d7
Author:    mchung
Date:      2016-02-05 15:12 -0800
URL:       http://hg.openjdk.java.net/jigsaw/jake/jdk/rev/54d2387b00d7

Exclude indy string concat tests until it's enabled

! test/ProblemList.jake.txt