Merge branch 'master' of https://github.com/google/blueprint into 20181226165820

* 'master' of https://github.com/google/blueprint:
  bpmodify: add argument if it is missing

Fixes: 121049769
Test: manual + use aidl_interface's *-freeze-api

Change-Id: I3c8fd1e8775fdee9aa33c02cc189101049c0f9b1