blt_add_benchmark should take CONFIGURATIONS and OMP_NUM_THREADS arguments

[skyreflectedinmirrors]

E.g., here:

blt/cmake/BLTMacros.cmake

Line 937 in 553a902

CONFIGURATIONS Benchmark)

Not only is this consistent with blt_add_test, but this enables e.g., creating your own configurations that specific benchmarks should be run on. For instance, I would like to create a "Multinode" configurations where only tests / benchmarks that require multiple nodes should be run (e.g., to benchmark inter-node bandwidth). This way I can create a Jenkins job or the like that only runs those tests when I allocate two+ nodes for a job.

Today, I have to do something like:

blt_add_test(...
                    CONFIGURATIONS Benchmark Multinode
)

I think this would be a minimally invasive PR, and I'd be happy to work on it if y'all agree.

[skyreflectedinmirrors]

Looking at it, it appears that NUM_OMP_THREADS is missing as well

[white238]

That's a great idea. We appreciate any help if you have time, otherwise I will handle it shortly.

[skyreflectedinmirrors]

started in #636

[white238]

Closed in #636