RFR(S): 8215975: [testbug] Adapt nsk tests to the PPC, S390 and AIX platforms.

[Lindenmaier, Goetz]

Hi,

Some of the nsk tests are not properly configured for the
above platforms:

 nsk/jvmti/RetransformClasses/retransform003/TestDriver.java: 
 nsk/jvmti/SetNativeMethodPrefix/SetNativeMethodPrefix002/TestDriver.java 
 The tests use the path to native libraries, which is named "LIBPATH" on AIX. 

 nsk/share/jdi/ArgumentHandler.java 
 Add ppc/s390/aix which don't have a shared memory connector. This disables a row of failing tests.

Please review this change. I would like to push it to jdk12, as it is a mere test fix.
http://cr.openjdk.java.net/~goetz/wr18/8215975-nskTests/01/index.html

Best regards,
  Goetz.