Add threading and multi-instance test for capgen

[climbfuji]

Description

We need tests that cover threading (OpenMP multiple threads) and multiple instances for capgen.

Solution

The tests should cover the following scenarios:

• one instance, single threaded vs multiple threads
• multiple instances, single threaded vs multiple threads

@climbfuji will be adding these tests, since supporting multiple instances is an NRL requirement

Alternatives (optional)

No alternative. Code that is untested is broken by definition.

Related to (optional)

#561

[gold2718]

What should the interface for using multiple instances be? One idea is to add an additional switch to capgen:

--multi-instance

which would generate code for 1 or more instances. This switch would require that number_of_ccpp_instances be available from the host model.

I think the instance number (ccpp_instance) must be required for suite caps. I suppose that could be optimized away if there were no suite variables?

[climbfuji]

Another option is to always generate multi-instance code, but default to one instance if number_of_ccpp_instances is not provided by the host model.

[gold2718]

Another option is to always generate multi-instance code, but default to one instance if number_of_ccpp_instances is not provided by the host model.

Do you have a preference? Are others okay with always having an extra dimension in suite variables?
@peverwhee, @dustinswales, @mkavulich ?

[climbfuji]

Another option is to always generate multi-instance code, but default to one instance if number_of_ccpp_instances is not provided by the host model.

Do you have a preference? Are others okay with always having an extra dimension in suite variables? @peverwhee, @dustinswales, @mkavulich ?

My preference is the solution that is easiest to implement and produces the least amount of code.