allow run-as to access /data/local/tmp

Otherwise denials like the following occur:

avc: denied { write } for path="/data/local/tmp/foo" dev="dm-0" ino=325769 scontext=u:r:runas:s0 tcontext=u:object_r:shell_data_file:s0 tclass=file
avc: denied { read } for path="/data/local/tmp/foo" dev="dm-0" ino=325769 scontext=u:r:runas:s0 tcontext=u:object_r:shell_data_file:s0 tclass=file

Steps to reproduce:

$ run-as com.google.android.talk id > /data/local/tmp/id.out
$ run-as com.google.android.talk cat < /data/local/tmp/id.out

Change-Id: I68a7b804336a3d5776dcc31622f1279380282030