Add four new tests for error the error handling cases:
  - gem_bad_address - store to a bad address, should generate a protection or
    page table error
  - gem_bad_batch - try to execute a bad batch, should generate a protection,
    invalid instruction or page table error
  - gem_bad_blit - blit to an invalid location, should generated a protection
    or page table error
  - gem_hang - hang the GPU on an event that will never happen, test hang
    detection & recovery code