Update git submodules

* Update system/gatekeeper from branch 'master'
  to 644ddd6370eb6a943d56c8021ed98cc72599d50e
  - Add host_supported to libgatekeeper.
    
    Bug: 155694128
    Test: m libgatekeeper
    Change-Id: I28d2be9deabb37ccdd71635cce6bd4b0c7d0c49c
    
1 file changed