Pump max number of threads

[mjklemm]

Increase the thread limit for barriers from 64 to 256 (256 ought to be enough :-))

[JimCownie]

That is fine, though it may be worth abstracting the MAX_THREADS out into a header which is used by all of the micro benchmarks, since there are definitions in a few places.

atomics.cc:51:#define MAX_THREADS 256
futex.cc:24:#define MAX_THREADS 512
loadsStores.cc:51:#define MAX_THREADS 512
locks.cc:49:#define MAX_THREADS 256

Or, you could remove them all and make it a cmake value.

[mjklemm]

Good suggestion. It was a bit of work, but it's now a CMake option.

[JimCownie]

LGTM