swift234

[driver] Fixed a bug in DummyTaskQueue where it would not generate unique ProcessIds.

Since DummyTaskQueue does not actually execute, it keeps a counter of
ProcessIds. This previously was a local variable; it is now static since
multiple instances of DummyTaskQueue may be used, depending on the requested
commands.

No tests for this yet, but this will be required to properly test parseable
output.

Swift SVN r20849