Add C++ toolchain team to OWNERS of abseil .def files

So we can update them during toolchain updates.

Change-Id: I3085f99be0ede4d288df6524f5e6c430cf61261f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6765997
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1488565}
NOKEYCHECK=True
GitOrigin-RevId: 99c3ab3809c2fb59413578a1fd9606d7eef842b2

OWNERS

diff --git a/OWNERS b/OWNERS
index 7826087..c93c059 100644
--- a/OWNERS
+++ b/OWNERS
@@ -2,4 +2,4 @@
 mbonadei@chromium.org
 
 # For .def files updates:
-hans@chromium.org
+per-file *.def=file://tools/clang/scripts/OWNERS