[RenderScript] Add API to map Allocation mallocptr to Java ByteBuffer

Bug: 25926361
Bug: 23535524

  - Construct the ByteBuffer using the AllocationGetPointer.
  - Add an API to query the stride of the allocation.
  - Both ByteBuffer and Stride will be cached for normal Allocations.
    if using USAGE_IO, since after each ioReceive, the mallocPtr will
    change, getByteBuffer will always create a new one using the most
    up-to-date mallocPtr.

Change-Id: I5e84b6690e83bb062c383043275524d0e51e46eb