Add on-the-fly cropping and rotation to jpegutil

Bug: 19323062

 * Adds another JpegUtilNative method for compression with a crop
   rectangle.
 * Improves speed of Jpeg compression with a non-zero rotation.
 * Fixes small native memory leak caused by not calling
   jpeg_destroy_compress() to free the libjpeg context.
 * Adds gunit tests for native code.

Change-Id: Id0aa5fd525fb232c4241a6b24970923f4f2c20df
6 files changed