* support/include/test_support.h, support/src/tmtests_empty_function.c:
Add helper so it is easier to write a basic repeated operation
tmtest.
* support/src/tmtests_support.c: New file.
* support/include/test_support.h, support/include/tmacros.h,
support/src/test_support.c: Added support functions to spin for a
number of ticks and to spin until the next tick.
* support/src/spin.c: New file.
