Update OWNERS files to reflect HWUI team work + ownership:

* Adding alecmouri@ and jreck@ to libui owners, removing vhau@ who has since switched teams.
* Adding alecmouri@ and jreck@ to librenderengine owners

Change-Id: I12bd249c079c88d7d05e1d4b9986703812c59bb4
diff --git a/libs/ui/OWNERS b/libs/ui/OWNERS
index 203a739..b1317b1 100644
--- a/libs/ui/OWNERS
+++ b/libs/ui/OWNERS
@@ -1,6 +1,7 @@
+alecmouri@google.com
 chrisforbes@google.com
+jreck@google.com
 lpy@google.com
 mathias@google.com
 romainguy@google.com
 stoza@google.com
-vhau@google.com