Add hansson to OWNERS for build files

Soong team has cleaned up their OWNERS file, so add back hansson
to the frameworks/base build file owners.

We'll explore migrating all the API related build rules into the
api subdir, which would allow removal from the global file.

Change-Id: Ie9f6a22376b49abec5e45c3b805e00d87361101d
diff --git a/OWNERS b/OWNERS
index 09a721f..198be3f 100644
--- a/OWNERS
+++ b/OWNERS
@@ -30,6 +30,7 @@
 # Support bulk translation updates
 per-file */res*/values*/*.xml = byi@google.com, delphij@google.com
 
+per-file **.bp,**.mk = hansson@google.com
 per-file *.bp = file:platform/build/soong:/OWNERS #{LAST_RESORT_SUGGESTION}
 per-file Android.mk = file:platform/build/soong:/OWNERS #{LAST_RESORT_SUGGESTION}
 per-file framework-jarjar-rules.txt = file:platform/build/soong:/OWNERS #{LAST_RESORT_SUGGESTION}