[8u]Request for enhancement backport approval for JDK-8077608 [TESTBUG] Enable Hotspot jtreg tests to run in agentvm mode

[Liu, Xin]

My  original aim is to solve JDK-8180904: Hotspot tests running with -agentvm failing due to classpath, which appears in Aleksey’s list:
https://builds.shipilev.net/backports-monitor/filter-openjdk-missing-8u212.txt

It turns out that jdk9 solved this problem by JDK-8077608, so I backported it to jdk8u-dev. Here is webrev.
http://cr.openjdk.java.net/~phh/8077608/webrev.8u.00/

I drop ‘compiler/uncommontrap/TestUnstableIfTrap.java’ because jdk8u-dev misses it. I verified all tests listed JDK-8180904<https://bugs.openjdk.java.net/browse/JDK-8180904> can pass with -agentvm.
Thanks,
--lx