omni: sepolicy: Add posix-type fs rules for sdcards.

Everything below holds for sdcards formatted with a
ext4 / f2fs or alike filesystem.

* Allow filesystem context relabeling from vold that is
  required to set the correct context.
* Grant access to the sdcard for untrusted_app,
  untrusted_app_25, priv_app, and platform_app.
* Label files & dirs below a corresponding sdcard with
  sdcard_posix (set in genfscontext).
* Allow installd to get the quota.
* Allow sdcard access for the mediaprovider.

Change-Id: I7b0347010e7bc11a461b0120f75095d5d6ad0c70
Signed-off-by: Alexander Diewald <Diewi@diewald-net.com>
diff --git a/sepolicy/genfs_contexts b/sepolicy/genfs_contexts
index 1dbd632..a9d564a 100644
--- a/sepolicy/genfs_contexts
+++ b/sepolicy/genfs_contexts
@@ -6,3 +6,4 @@
 genfscon fuseblk / u:object_r:fuse_device:s0
 genfscon exfat / u:object_r:exfat:s0
 genfscon ntfs / u:object_r:ntfs:s0
+genfscon sdcard_posix / u:object_r:sdcard_posix:s0