Add tobiast@ to OWNERS

Add tobiast@ to OWNERS; libcore have a test that is affected
by this code.

Test: None
Change-Id: I98026f6092a4f61284e614ac37d2e0a31e210ad0
diff --git a/OWNERS b/OWNERS
index b5b393f..0aa182a 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,7 +1,5 @@
-# Default owners are top 3 active developers of the past 1 or 2 years
-# or people with more than 10 commits last year.
-# Please update this list if you find better owner candidates.