Allow installd to unlink /data/media files and search /data/app-asec.

Address recent installd denials resulting from the recent
tightening of installd access to /data file types, including:
 avc:  denied  { unlink } for  name="._playmusicid" dev="mmcblk0p30" ino=1038393 scontext=u:r:installd:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=file
 avc:  denied  { search } for  pid=195 comm="installd" name="app-asec" dev="mmcblk0p28" ino=578225 scontext=u:r:installd:s0 tcontext=u:object_r:asec_image_file:s0 tclass=dir

Change-Id: I957738139678699949da9ad09d3bddb91605f8cf
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>