* Refactor basic/intmath tests into a single file
These six tests previously duplicated almost all of their sources in
separate files. Bring them into a single file with templated routines
to perform the tests.
This change also makes use of more C++ features and utilities from the
harness library to make the code cleaner.
* Fix array indices for initialization
* Use loop for buffer creation
* Refactor to remove duplicate verification code
Remove need for hardcoded number of test operations.
* Address review comments
* Use TEST_SKIPPED_ITSELF
