Create vdc domain

The init.rc one-shot services "defaultcrypto" and "encrypt" call
out to the /system/bin/vdc command line to ask vold to perform
encryption operations. Create a new domain for these one-shot
services. Allow the vdc domain to talk to vold.

Change-Id: I73dc2ee4cc265bc16056b27307c254254940fd9f

file_contexts

@@ -158,6 +158,7 @@
 /system/bin/logd        u:object_r:logd_exec:s0
 /system/bin/uncrypt     u:object_r:uncrypt_exec:s0
 /system/bin/logwrapper  u:object_r:system_file:s0
+/system/bin/vdc         u:object_r:vdc_exec:s0
 #############################
 # Vendor files
 #

vdc.te

+# vdc spawned from init for the following services:
+#  defaultcrypto
+#  encrypt
+
+type vdc, domain;
+type vdc_exec, exec_type, file_type;
+
+init_daemon_domain(vdc)
+
+unix_socket_connect(vdc, vold, vold)