Allow adbd / shell /data/anr access

The shell user needs to be able to run commands like
"cat /data/anr/traces.txt". Allow it.

We also need to be able to pull the file via adb.
"adb pull /data/anr/traces.txt". Allow it.

Addresses the following denials:

<4>[   20.212398] type=1400 audit(1402000262.433:11): avc: denied { getattr } for pid=1479 comm="adbd" path="/data/anr/traces.txt" dev="mmcblk0p28" ino=325763 scontext=u:r:adbd:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file
<4>[   20.252182] type=1400 audit(1402000262.473:12): avc: denied { read } for pid=1479 comm="adbd" name="traces.txt" dev="mmcblk0p28" ino=325763 scontext=u:r:adbd:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file
<4>[   20.252579] type=1400 audit(1402000262.473:13): avc: denied { open } for pid=1479 comm="adbd" name="traces.txt" dev="mmcblk0p28" ino=325763 scontext=u:r:adbd:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file
<4>[   27.104068] type=1400 audit(1402000268.479:14): avc: denied { read } for pid=2377 comm="sh" name="traces.txt" dev="mmcblk0p28" ino=325763 scontext=u:r:shell:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file

Bug: 15450720
Change-Id: I767102a7182895112838559b0ade1cd7c14459ab