core/jni/android/graphics: Cache copy of pre-scaled Bitmaps

Caching some pre-scaled Bitmap objects allows for optimizing later
scaling operations to reduce memory pressure.

CRs-fixed: 451681

Change-Id: Id4341e75911074ff9f565b2d386ccad8f3a223e8
Merge remote-tracking branch 'sgt7/cm-10.1' into cm-10.1-sgt7-linaro