Number of iterations of chained suites not used. #81

Hey there, nice project! I have been using it a bunch, in particular the suites of suites feature. One use case for me is having a suite dedicated for benchmark tests with high number of iterations. I use the main suite for unit tests with 1 iteration and the second (chained) suite for benchmarks with 10000 iterations. It seems that the number of iterations of the main suite overrides the others, so all my tests run 1 time only. Is this by design? As a workaround, I am using `MUNIT_TEST_OPTION_SINGLE_ITERATION` in my unit test functions and setting the main suite to run 1000 iterations. This solves the problem apparently, however, all other suites will also run 10000 times if not using the single iteration option. I think it would be more flexible to get the number of iterations from each test suite, no?