SEPolicy for Staged Installs.

Test: basic workflow between apexd and PackageManager tested with
changes being developed.
Bug: 118865310
Change-Id: I1ae866f33e9b22493585e108c4fd45400493c7ac
diff --git a/private/file_contexts b/private/file_contexts
index 13d87ff..da41ef7 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -429,6 +429,7 @@
 /data/preloads/media(/.*)?	u:object_r:preloads_media_file:s0
 /data/preloads/demo(/.*)?	u:object_r:preloads_media_file:s0
 /data/server_configurable_flags(/.*)? u:object_r:server_configurable_flags_data_file:s0
+/data/staging(/.*)?		u:object_r:staging_data_file:s0
 
 # Misc data
 /data/misc/adb(/.*)?            u:object_r:adb_keys_file:s0