Add read bandwidth and small refactor.

Add read bandwidth and small refactor.

- Addition of read bandwidth test.
- Move the allocation of all buffers used for testing into the
  setSize() function.
- Add a canRun function to indicate whether a test is able to
  run on this platform. Currently, this only disables neon bandwidth
  tests on platforms that don't support neon.
- Refactor the thread testing functions to use one common routine.

Change-Id: I4ebed7d20100f57e93fd10bbe9dbbb53b50cd4a6