Grant platform apps access to /mnt/media_rw.

Raw physical storage devices are mounted by vold under /mnt/media_rw
and then wrapped in a FUSE daemon that presents them under /storage.

Normal apps only have access through /storage, but platform apps
(such as ExternalStorageProvider) often bypass the FUSE daemon for
performance reasons.

avc: denied { search } for pid=6411 comm="Binder_1" name="media_rw" dev="tmpfs" ino=6666 scontext=u:r:platform_app:s0:c512,c768 tcontext=u:object_r:mnt_media_rw_file:s0 tclass=dir
avc: denied { write } for pid=3701 comm="Binder_2" name="PANO_20131016_162457.jpg" dev="sda1" ino=127 scontext=u:r:platform_app:s0:c522,c768 tcontext=u:object_r:vfat:s0 tclass=file

Bug: 19993667
Change-Id: I66df236eade3ca25a10749dd43d173ff4628cfad
1 file changed