Adding bbudge to src/compiler OWNERS (focus on backend).

R=jarin@chromium.org

Bug: 
Change-Id: I43c72aa222a6b41b22b3f80f3d4ce3113b965a81
Reviewed-on: https://chromium-review.googlesource.com/822526Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50096}

src/compiler/OWNERS

@@ -3,13 +3,16 @@ set noparent
 bmeurer@chromium.org
 jarin@chromium.org
 mstarzinger@chromium.org
-mtrofin@chromium.org
 titzer@chromium.org
 danno@chromium.org
 tebbi@chromium.org
 neis@chromium.org
 mvstanton@chromium.org
 
+# For backend
+bbudge@chromium.org
+mtrofin@chromium.org
+
 per-file wasm-*=ahaas@chromium.org
 per-file wasm-*=bbudge@chromium.org
 per-file wasm-*=bradnelson@chromium.org