Let qemu_props service set system properties in ro.emu and ro.emulator

These boot properties are used by android wear emulator to configure
round and chin shaped devices.

Bug: 23324757
Change-Id: I812da02d771bba0ffc63b14459c7de7cbdeed142
diff --git a/target/board/generic/sepolicy/property_contexts b/target/board/generic/sepolicy/property_contexts
index 09b9b06..a0a4020 100644
--- a/target/board/generic/sepolicy/property_contexts
+++ b/target/board/generic/sepolicy/property_contexts
@@ -1,2 +1,4 @@
 qemu.                   u:object_r:qemu_prop:s0
+emu.                    u:object_r:qemu_prop:s0
+emulator.               u:object_r:qemu_prop:s0
 radio.noril             u:object_r:radio_noril_prop:s0