[Depends] Update dependency fallback URL
[Depends] Update dependency fallback URL

Since our dependencies do not precisely match upstream's, we need to
have our own fallback URL to use in the event that any of the original
URLs are non-functioning.

This takes care of the issue.

PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,PIVX-Project/PIVX