Update git submodules

* Update prebuilts/build-tools from branch 'master'
  to e2c1c1d8f8874e310fe7a7090ae670d7a6c5c5cb
  - Remove makeparallel from the build script
    
    makeparallel is no longer necessary, and has been removed.
    
    Test: treehugger
    Change-Id: I41cbaf79b98c82ab9cf5d986576896990a4f8162
    
1 file changed