hg: code-tools/jtreg: change to use -source 8 -target 8 for the main tool; version to 5.0

[jonathan.gibbons at oracle.com]

Changeset: 03c4dff80b0f
Author:    jjg
Date:      2020-02-05 14:14 -0800
URL:       https://hg.openjdk.java.net/code-tools/jtreg/rev/03c4dff80b0f

change to use -source 8 -target 8 for the main tool; version to 5.0

! make/Defs.gmk
! make/build.properties
! make/build.xml