Initial selinux policy support for memfd

Move all app tmpfs types to appdomain_tmpfs. These are still protected
by mls categories and DAC. TODO clean up other app tmpfs types in a
separate change.

Treble-ize tmpfs passing between graphics composer HAL and
surfaceflinger.

Bug: 122854450
Test: boot Blueline with memfd enabled.
Change-Id: Ib98aaba062f10972af6ae80fb85b7a0f60a32eee
diff --git a/private/system_server.te b/private/system_server.te
index 1003994..f91461c 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -13,6 +13,7 @@
 type_transition system_server system_data_file:sock_file system_ndebug_socket "ndebugsocket";
 
 allow system_server zygote_tmpfs:file read;
+allow system_server appdomain_tmpfs:file { getattr map read write };
 
 # For art.
 allow system_server dalvikcache_data_file:dir r_dir_perms;