RFR 9 8055330: (process spec) ProcessBuilder.start and Runtime.exec should throw UnsupportedOperationException ...

[Roger Riggs]

Please review this clarification to the optional behavior of 
java.lang.Runtime and java.lang.ProcessBuilder
on platforms that don't support process creation.

Webrev:
  http://cr.openjdk.java.net/~rriggs/webrev-process-8055330/
Issue:
 8055330 https://bugs.openjdk.java.net/browse/JDK-8055330

ps: approved by CCC