RFR(s): 8179327: gtestLauncher should run tests on a separate thread (optionally)

[Thomas Stüfe]

Dear all,

please review the following change:

Bug: JDK-8179327 <https://bugs.openjdk.java.net/browse/JDK-8179327>
Webrev: http://cr.openjdk.java.net/~stuefe/webrevs/
8179327-gtestLauncher-should-have-an-option-to-avoid-
primordial-thread-for-tests/webrev.00/webrev/

This fix is motivated by the inability of the AIX openjdk vm to run on the
primordial thread (see https://bugs.openjdk.java.net/browse/JDK-8171505),
which we unfortunately cannot do much about. This prevented us until now to
run gtests successfully, because the gtestlauncher (in contrast to the
standard java launcher) invokes the VM on the primordial thread.

To fix this, I gave the gtest launcher the ability to run the tests in an
own thread. Instead of sprinkling the source with "#ifdef _AIX", I added a
command line option "-new-thread", which allows to start the tests in a new
thread, and implemented this feature for all platforms (well, posix and
windows). On all platforms save AIX this is by default off, so nothing
changes. On AIX, tests will be default be executed in a new thread.

Thanks for reviewing,

Kind Regards, Thomas