See https://groups.google.com/d/msg/android-ndk/BbEOA9pnR-I/HgLkGy5qAgAJ

Addresses the following denial:

  avc: denied { lock } for path="/data/data/com.mypackage/files/somefilename" dev="mmcblk0p28" ino=114736 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir permissive=0

While I'm here, also add lock to w_file_perms.

(cherrypicked from commit 4ee494cc)

Change-Id: I2568a228099c4e112e4a8b80da3bfcf2e35eb0ea