RFR(M): 8068013: [TESTBUG] Aix support in hotspot jtreg tests

[Lindenmaier, Goetz]

Hi,

A row of hotspot jtreg tests fail because support to test for Aix is missing.
To pass them, I would like to submit the following fixes:

* runtime/6888954/vmerrors.sh: AIX can read from address '0', then throws SIGILL.
* serviceability/dcmd/DynLibDcmdTest.java: Just add check for Aix.
* test/test_env.sh: Add support for AIX. Sort OSes alphabetical.
* test/testlibrary/com/oracle/java/testlibrary/Platform.java: add isAix(). Sort OSes alphabetical.

Please review this change, and I please need a sponsor.
http://cr.openjdk.java.net/~goetz/webrevs/8068013-jtregAix/webrev-01/

Thanks and best regards,
  Goetz.