sepolicy: Fix policy for keyhandler

Change-Id: I2860f469480b082511e30530aed8a9027e9fe4b9
diff --git a/sepolicy/system.te b/sepolicy/system.te
index c75d4c3..59b5109 100644
--- a/sepolicy/system.te
+++ b/sepolicy/system.te
@@ -8,4 +8,4 @@
 allow system_server dhcp_data_file:file r_file_perms;
 
 # System server dynamically loads some dexfiles
-allow system_server dex2oat_exec:file execute;
+allow system_server dex2oat_exec:file rx_file_perms;