Added supplemental key to the sepolicy

Allows apps to be signed with the supplemental key

Bug: 203670791
Test: Make, device boots
Ignore-AOSP-First: Feature is developed in internal branch

Change-Id: I2215ffe74e0fa19ff936e90c08c4ebfd177e5258
diff --git a/private/mac_permissions.xml b/private/mac_permissions.xml
index 7fc37c1..0e77637 100644
--- a/private/mac_permissions.xml
+++ b/private/mac_permissions.xml
@@ -51,6 +51,11 @@
       <seinfo value="platform" />
     </signer>
 
+    <!-- Supplemental process key -->
+    <signer signature="@SUPPLEMENTAL_PROCESS" >
+      <seinfo value="supplemental_process" />
+    </signer>
+
     <!-- Media key in AOSP -->
     <signer signature="@MEDIA" >
       <seinfo value="media" />