runtime: use gList for work.sweepWaiters
runtime: use gList for work.sweepWaiters

Change-Id: Ibae474a5c9a3528a042ddf19ddb4a88913a87606
Reviewed-on: https://go-review.googlesource.com/129399
Run-TryBot: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Rick Hudson <838bd060584c511f21c75c69ea04b7b120d86af0@golang.org>

golang/go,akutz/go,cloudflare/go,nawawi/go,golang/go,nawawi/go,josharian/go,cloudflare/go,cloudflare/go,CAFxX/go,cloudflare/go,josharian/go,nawawi/go,nawawi/go,josharian/go,golang/go,josharian/go,akutz/go,cloudflare/go,golang/go,golang/go,cloudflare/go,akutz/go,golang/go,nawawi/go,CAFxX/go,golang/go,josharian/go,CAFxX/go,CAFxX/go,nawawi/go,nawawi/go,CAFxX/go,CAFxX/go,akutz/go,josharian/go,akutz/go,cloudflare/go,akutz/go,cloudflare/go,josharian/go,akutz/go,josharian/go,nawawi/go,golang/go,akutz/go,CAFxX/go,CAFxX/go