bgpq3 0.1.21

Bumping from 0.1.19 to 0.1.21 which contains new features and a small
fix for MacOSX.

Closes #29930.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
sqsh 2.5.16.1
bgpq3: add 0.1.21 bottle.
sqsh: add 2.5.16.1 bottle.