allow untrusted_app read /data/anr/traces.txt

The GMS core feedback agent runs as untrusted_app, and needs
the ability to read /data/anr/traces.txt to report ANR information.

Allow all untrusted_apps to read /data/anr/traces.txt so that GMS core
can access it.

Longer term, we need to move GMS core into it's own domain, but that's
a longer term change.

Addresses the following denial:

W/ndroid.feedback(17825): type=1400 audit(0.0:68004): avc: denied { read } for name="traces.txt" dev="mmcblk0p28" ino=325762 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file

Bug: 18504118
Bug: 18340553
Change-Id: Ia9fac599befc3a3b6e5282be15ec8fd04bb23385
1 file changed