sepolicy: Add iorap_prefetcherd rules

/system/bin/iorapd fork+execs into /system/bin/iorap_prefetcherd during
startup

See also go/android-iorap-security for the design doc

Bug: 137403231
Change-Id: Ie8949c7927a98e0ab757bc46230c589b5a496360
diff --git a/private/iorapd.te b/private/iorapd.te
index 91f4ddc..ba8ece3 100644
--- a/private/iorapd.te
+++ b/private/iorapd.te
@@ -2,3 +2,5 @@
 
 init_daemon_domain(iorapd)
 tmpfs_domain(iorapd)
+
+domain_auto_trans(iorapd, iorap_prefetcherd_exec, iorap_prefetcherd)