build: Move buildroots to cache/
build: Move buildroots to cache/

So it's clear that you can rm -rf them at any time.

chergert/gnome-continuous,vrutkovs/vrutkovs.github.io,chergert/gnome-continuous,djdeath/gnome-ostree,djdeath/gnome-ostree,GNOME/gnome-ostree,GNOME/gnome-ostree,GNOME/gnome-ostree,vrutkovs/vrutkovs.github.io,djdeath/gnome-ostree,vrutkovs/vrutkovs.github.io,chergert/gnome-continuous