hg: code-tools/jtharness: Make serial agent's compilation optional

[alexey.fedorchenko at oracle.com]

Changeset: 6f47d2bd87c1
Author:    afedorch
Date:      2017-03-07 19:01 +0300
URL:       http://hg.openjdk.java.net/code-tools/jtharness/rev/6f47d2bd87c1

Make serial agent's compilation optional

! build/build.xml
! src/com/sun/javatest/agent/AgentApplet.java
! src/com/sun/javatest/agent/AgentFrame.java
! src/com/sun/javatest/agent/AgentPanel.java