Add bspatch to update_engine_exec.

This allow bspatch to have same perssion as update_engine.

Also added a rule to allow update_engine to execute bspatch.

Bug: 24478450
Test: No more permission deny during delta update.

Change-Id: If94bc703b2f3fc32f901f0d7f300934316d4e9a4
diff --git a/file_contexts b/file_contexts
index 942b7e6..a74f8f8 100644
--- a/file_contexts
+++ b/file_contexts
@@ -200,6 +200,7 @@
 /system/bin/tzdatacheck u:object_r:tzdatacheck_exec:s0
 /system/bin/idmap u:object_r:idmap_exec:s0
 /system/bin/update_engine        u:object_r:update_engine_exec:s0
+/system/bin/bspatch              u:object_r:update_engine_exec:s0
 
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 # Vendor files