Merge changes from topic 'am-02585df899244ddfb0b2ea27e62c017d'

* changes:
  e2fsdroid: use libselinux function to read file context on device am: 2fff6fb036 am: 3ac608fd1b  -s ours
  Require mke2fs.conf when building mke2fs am: 778eaa84a0 am: 6243f2136f  -s ours