Update git submodules

* Update platform/prebuilts/build-tools from branch 'master'
  to 590d7852373de81b51b000585a744e7acc309ead
  - Merge "Update build-tools to ab/5661346"
  - Update build-tools to ab/5661346
    
    https://ci.android.com/builds/branches/aosp-build-tools/grid?head=5661346&tail=5661346
    
    Test: treehugger
    Change-Id: Ie14c077acc9c5f35e8fb98041227c5b4431d274e
    

* Update platform/superproject from branch 'master'
  to b3447cba6276ba1b2881aa8fec6a9c49a6e1b15c
  - Update git submodules
    
    * Update prebuilts/build-tools from branch 'master'
      to 590d7852373de81b51b000585a744e7acc309ead
      - Merge "Update build-tools to ab/5661346"
      - Update build-tools to ab/5661346
        
        https://ci.android.com/builds/branches/aosp-build-tools/grid?head=5661346&tail=5661346
        
        Test: treehugger
        Change-Id: Ie14c077acc9c5f35e8fb98041227c5b4431d274e
        
2 files changed