runtime: add new deltimer function
runtime: add new deltimer function

Updates #27707

Change-Id: I720e8af9e183c75abcb63ccc30466734c8dba74f
Reviewed-on: https://go-review.googlesource.com/c/go/+/171831
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Michael Knyszek <4473450dc5c88f06e1fb787f303d7805ec2aee65@google.com>

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