crash_dump: allow read of APK files.

Fixes type=1400 audit(0.0:3901): avc: denied { open } for comm="crash_dump32" path="/data/app/com.chrome.canary-H8gGiCrQUqTZha2IybgrlA==/base.apk" dev="sda35" ino=1384523 scontext=u:r:crash_dump:s0:c522,c768 tcontext=u:object_r:apk_data_file:s0 tclass=file permissive=1

Bug: http://b/34978531
Change-Id: I0374145f71059c3f104055bf4e8dcf08b1101f2a