fix an instance of bugprone-unused-return-value This new clang-tidy check fires when the result of a function like `unique_ptr.release()` is unused. Sometimes this is intentional, other times, it's not (e.g., the dev intended to `.reset()`). Bug: chromium:1134714 Change-Id: I9b6bc9e847e5c27d68707a4f33d37b225ded34fb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2458188 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>