RFR: 8167600 jib make run-test for langtools and intermittent failures on windows-x86

[Tim Bell]

Please review this rework of the langtools/test/Makefile fix done in 
8166648. [1]  ARCH_DATA_MODEL is not set in all test scenarios, so a 
better approach is to check the VM about to be tested.

Bug report:
     https://bugs.openjdk.java.net/browse/JDK-8167600

Webrev:
     http://cr.openjdk.java.net/~tbell/8167600/webrev.00/

Testing:
    Successful JPRT runs on all platforms.  Inspected the 
<platform>_<arch>.product-c2-langtools_jtreg.log files to verify the 
expected flag was used only on 32-bit VMs.


Thanks in advance-

Tim

[1] JDK-8166648 https://bugs.openjdk.java.net/browse/JDK-8166648