Allow mediaextractor to load libraries from apk_data_file

This is an experimental feature only on userdebug and eng build.

Test: play MP4 file. install & uninstall media update apk.
Bug: 67908547
Change-Id: I513cdbfda962f00079e886b7a42f9928e81f6474
diff --git a/private/service_contexts b/private/service_contexts
index c1ea51a..373c7cc 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -88,6 +88,7 @@
 media.player                              u:object_r:mediaserver_service:s0
 media.metrics                             u:object_r:mediametrics_service:s0
 media.extractor                           u:object_r:mediaextractor_service:s0
+media.extractor.update                    u:object_r:mediaextractor_update_service:s0
 media.codec                               u:object_r:mediacodec_service:s0
 media.resource_manager                    u:object_r:mediaserver_service:s0
 media.sound_trigger_hw                    u:object_r:audioserver_service:s0