Update git submodules

* Update external/googletest from branch 'master'
  to 60520b3a4cb0316e171ad0cae2aa48215b6180f7
  - Switch to system/core/janitors as OWNERS.
    
    Change-Id: I992d23eb080f2027dcf6af5ea6b09b05fdd0a96d
    
1 file changed