Minor changes and fixes.

Details:
- Redefined bli_is_last_iter() to take thread_id and num_thread
  arguments, which allows the macro to correctly compute whether a
  given iteration is the last that the thread will compute in that
  particular loop. The new definition, however, remains disabled
  (commented out) until someone can look at this more closely, as
  the new definition seems to actually hurt performance slightly.
- Whitespace and related updates to level-3 macro-kernels.
- Updated test suite so that performance results in the hundreds of
  gigaflops does not disrupt the column alignment of the output.
Use correct definition of bli_is_last_iter().

Details:
- As intended for previous commit, the new definition of
  bli_is_last_iter() is now disabled in favor of the old
  definition.