GroupThreads all remainig

[thurston at nomagicsoftware.com]

I was curious whether there is a way to specify like the following:



@Group("abc")
@GroupThreads(1)
@Benchmark
......

@Group("abc")
@GroupThreads(*)
@Benchmark
.....

Where the star would indicate "all of the rest of the threads"

I realize the value parameter is an int, so something like -1 could 
serve as the indicator.

I tend to set the benchmark threads from the command-line, and it would 
be a lot easier to just compile the benchmark once