Add selinux policies for pac_proxy_service

The policies allow system server to register a pac_proxy_service.

Bug: 177035719
Test: FrameworksNetTests

Change-Id: Idf64dc6e491f5bce66dcab2dbf15823c8d0c2403
diff --git a/private/service_contexts b/private/service_contexts
index f522323..6c62603 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -190,6 +190,7 @@
 oem_lock                                  u:object_r:oem_lock_service:s0
 otadexopt                                 u:object_r:otadexopt_service:s0
 overlay                                   u:object_r:overlay_service:s0
+pac_proxy                                 u:object_r:pac_proxy_service:s0
 package                                   u:object_r:package_service:s0
 package_native                            u:object_r:package_native_service:s0
 people                                    u:object_r:people_service:s0