Fix DngCreatorTest memory usage and tonemapping.

- Handle java heap allocations more carefully to avoid
  OOM errors for high MP devices.
- Fix the tonemapping coefficients to use a pre-gamma
  correction tonemapping curve rather than post-gamma
  correction (oops).

Bug: 21661705
Change-Id: I65a5eae9c5c6ec96e88a11baab762f2f7caf95c8
2 files changed