Add /dev/socket/uncrypt.

system_server used to communicate with uncrypt via files (e.g.
/cache/recovery/command and /cache/recovery/uncrypt_status). Since A/B
devices may not have /cache partitions anymore, we switch to communicate
via /dev/socket/uncrypt to allow things like factory reset to keep
working.

Bug: 27176738
Change-Id: I73b6d6f1ecdf16fd4f3600b5e524da06f35b5bca
diff --git a/file_contexts b/file_contexts
index e94c95e..c874a94 100644
--- a/file_contexts
+++ b/file_contexts
@@ -116,6 +116,7 @@
 /dev/socket/racoon	u:object_r:racoon_socket:s0
 /dev/socket/rild	u:object_r:rild_socket:s0
 /dev/socket/rild-debug	u:object_r:rild_debug_socket:s0
+/dev/socket/uncrypt	u:object_r:uncrypt_socket:s0
 /dev/socket/vold	u:object_r:vold_socket:s0
 /dev/socket/wpa_eth[0-9] u:object_r:wpa_socket:s0
 /dev/socket/wpa_wlan[0-9] u:object_r:wpa_socket:s0