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>