camera2: Fix native ImageReader test segfaults.

Bug: 17675571

- Check for JPEG footer in correct location from ImageReader
  when using the RGBA override.
- Add additional error checks in produceFrame method.
- Avoid allocating extra space for jpeg buffers due to
  incorrect width calculations.

Change-Id: I926f37e8b3e5c4bad24c16dcee48d52adb1706dd