Add tests for afdo.go

Bug: 79161490
Test: presubmit
Change-Id: I686b5226aad5011ab30a0a105f8c7866cd610502
diff --git a/cc/OWNERS b/cc/OWNERS
index 811d881..a7e6ebb 100644
--- a/cc/OWNERS
+++ b/cc/OWNERS
@@ -1,4 +1,4 @@
 per-file ndk_*.go = danalbert@google.com
 per-file tidy.go = srhines@google.com, chh@google.com
-per-file afdo.go,lto.go,pgo.go = srhines@google.com, pirama@google.com, yikong@google.com
+per-file afdo.go,afdo_test.go,lto.go,pgo.go = srhines@google.com, pirama@google.com, yikong@google.com