[incremental] allow system server to read /proc/filesystems

Also allow binder service "incremental_service" to be found by service
manager.

Test: boots
BUG: 136132412
Change-Id: I3584a9b69a7e1909f096e3c4579c1834bdfba22e
diff --git a/private/system_server.te b/private/system_server.te
index 5bd4d9d..73e4399 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -17,6 +17,9 @@
 allow system_server zygote_tmpfs:file read;
 allow system_server appdomain_tmpfs:file { getattr map read write };
 
+# For Incremental Service to check if incfs is available
+allow system_server proc_filesystems:file r_file_perms;
+
 # For art.
 allow system_server dalvikcache_data_file:dir r_dir_perms;
 allow system_server dalvikcache_data_file:file r_file_perms;