Update armnn to version 21.08 / rev 18 via SR 917697
    
    https://build.opensuse.org/request/show/917697
    by user Guillaume_G + dimstar_suse
    - Update to 21.08:
      * Changelog: https://github.com/ARM-software/armnn/releases/tag/v21.08
      * Main changes:
        - new capabilities and improve performance:
          * Added the ability to import protected DMA Buffers and
          allow Arm NN to run inferences that are in Protected GPU Memory.
          As well as providing Custom Memory Allocator which supports
          importing malloc, Dma_buf and protected Dma buffers.
          * Users with multi core NPUs has been given the ability to pin
          inferences to selected cores giving them the ability to balance
          parallel workloads across the NPU and increase throughput.
          * Boost has been completely removed from the code base making
          Arm NN easier to integrate into other software stacks.
          * Added support for non-constant weights and b