swift 2.21.0 release

meta:version: 2.21.0
meta:diff-start: -
meta:series: stein
meta:release-type: release
meta:pypi: no
meta:first: no
meta:release:Author: Tim Burke <tim.burke@gmail.com>
meta:release:Commit: Tim Burke <tim.burke@gmail.com>
meta:release:Change-Id: Ia199baf7ccad97bc294fe3d69c7904dceaae7adf
meta:release:Code-Review+2: Sean McGinnis <sean.mcginnis@gmail.com>
meta:release:Code-Review+1: John Dickinson <me@not.mn>
meta:release:Code-Review+2: Tony Breeds <tony@bakeyournoodle.com>
meta:release:Workflow+1: Sean McGinnis <sean.mcginnis@gmail.com>
-----BEGIN PGP SIGNATURE-----
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=Vc/+
-----END PGP SIGNATURE-----