Allow system_app to start bugreport and to create /data/anr/traces.txt.

Resolves denials such as:

avc:  denied  { set } for property =ctl.bugreport scontext=u:r:system_app:s0 tcontext=u:object_r:ctl_default_prop:s0 tclass=property_service

avc:  denied  { write } for  pid=4415 comm=5369676E616C2043617463686572 name="anr" dev="dm-0" ino=358337 scontext=u:r:system_app:s0 tcontext=u:object_r:anr_data_file:s0 tclass=dir

avc:  denied  { add_name } for  pid=4415 comm=5369676E616C2043617463686572 name="traces.txt" scontext=u:r:system_app:s0 tcontext=u:object_r:anr_data_file:s0 tclass=dir

avc:  denied  { create } for  pid=4415 comm=5369676E616C2043617463686572 name="traces.txt" scontext=u:r:system_app:s0 tcontext=u:object_r:anr_data_file:s0 tclass=file

Change-Id: I71d0ede049136d72f28bdc85d52fcefa2f7d128f
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>