Update git submodules

* Update platform/prebuilts/build-tools from branch 'master'
  to bbc516223436a544c27b4bd8d04e58e19379528d
  - Merge changes Ic07050a8,Idae22d9e
    
    * changes:
      Update build-tools to ab/8162587
      Add musl sysroot to update-prebuilts.sh
    
  - Update build-tools to ab/8162587
    
    https://ci.android.com/builds/branches/aosp-build-tools-release/grid?head=8162587&tail=8162587
    
    Test: treehugger
    Change-Id: Ic07050a8ff3ee1fa4ace3eeccc8fdc1b3605bd43
    
  - Add musl sysroot to update-prebuilts.sh
    
    Bug: 215802826
    Test: update-prebuilts.sh
    Change-Id: Idae22d9e219f3049b125ee96a055ef8e681a60d1