RFR: JDK-8217626 Add setup/teardown functionality to RunTest

Wed Jan 23 10:08:39 UTC 2019

Recently, jcov support was added to RunTest. This highlighted the need 
to have a structured way to run environment setup/teardown code before 
and after running all tests.

This fix will also back out the additional creation oj jcov-test-* 
targets from JDK-8215729, which goes contrary to the current effort of 
reducing the number of generated targets.

Bug: https://bugs.openjdk.java.net/browse/JDK-8217626
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8217626-rework-jcov-runtest-integration/webrev.01

/Magnus