Update git submodules

* Update prebuilts/build-tools from branch 'master'
  to 9867042b2ca10d3e718ad60927efe9af25b8f994
  - Add m4 to the prebuilt build-tools
    
    Bug: 117561006
    Test: OUT_DIR=out DIST_DIR=dist prebuilts/build-tools/build-prebuilts.sh
    Change-Id: Ic44d3640e9bbdc776a93dd2f44a767b082bc7c21
    
1 file changed