RFR(xs): 8171433: [aix] switch on gtest AIX build

[Thomas Stüfe]

Hi all,

Please review this tiny change.

Note that this was already part of the review of 8171225. I decided to
split that patch into multiple patches. This patch here just switches on
building of gtest on AIX by default (it was disabled due to build errors
before).

Issue:  https://bugs.openjdk.java.net/browse/JDK-8171433
Webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8171433-aix-switch-on-gtest-make-by-default/webrev.00/webrev/index.html

Kind Regards, Thomas