Update OWNERS for external/gemmlowp.

Test: n/a
Change-Id: I75fb3ea4ce62c7fc7fea321aeab48863787eb5c1
diff --git a/OWNERS b/OWNERS
index e05da8e..e5412e2 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1 +1,2 @@
 miaowang@google.com
+ianhua@google.com