Someone hop in if I am going about this the wrong way.
Check the file /usr/pkgsrc/wip/mk/fetch/sites.conf
That might help.
You could also search out a location and add a custom master site for your missing source file, by adding it to mk.conf
Code:
MASTER_SITE_ELEMENTARY-ICON-THEME+=
https://launchpad.net/elementaryicons/+download
I've never done that before. I usually just download the source file and add it to my local distfiles folder.
This will only fix your issue with this one file.