Update git submodules

* Update hardware/libhardware from branch 'master'
  to 681881da02360a340168422212501739dc0e33b6
  - Merge "Use bssl::UniquePtr."
  - Use bssl::UniquePtr.
    
    BoringSSL provides std::unique_ptr adapters now, so no need to
    reimplement custom ones.
    
    Test: mma
    Change-Id: Ia611761e99551b9583b459a04ffa79de9fb08210
    
1 file changed