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/file_contexts b/private/file_contexts
index 3e989e7..ac22908 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -289,6 +289,7 @@
 /system/bin/viewcompiler     u:object_r:viewcompiler_exec:s0
 /system/bin/profman(d)?     u:object_r:profman_exec:s0
 /system/bin/iorapd          u:object_r:iorapd_exec:s0
+/system/bin/iorap\.prefetcherd u:object_r:iorap_prefetcherd_exec:s0
 /system/bin/sgdisk      u:object_r:sgdisk_exec:s0
 /system/bin/blkid       u:object_r:blkid_exec:s0
 /system/bin/tzdatacheck u:object_r:tzdatacheck_exec:s0