RFR: 8258799 : [Testbug] RandomCommandsTest must check if tested directive is added via jcmd

[Nils Eliasson]

RandomCommandsTest.java is checking a mix of valid and invalid compilecommands and compiler directives. When they fail they have different behaviour:

A compilecommand that is malformed will result in a printed error, and then the VM continues. 
A compiler directive that is malformed, that is added via commandline, will abort the VM, much like any other VM-flag would. 
A compiler directive that is malformed, that is added via jcmd will print an error, and the VM continues - just like with any other jcmd.

The RandomCommandsTest fails when generating a malformed compiler directive and adding it via jcmd - because it expects the VM to abort.

This patch fixes that.

-------------

Commit messages:
 - fix whitespace
 - remove tabs
 - Check if directive added via jcmd is valid

Changes: https://git.openjdk.java.net/jdk/pull/2364/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2364&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258799
  Stats: 19 lines in 2 files changed: 16 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2364.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2364/head:pull/2364

PR: https://git.openjdk.java.net/jdk/pull/2364