guix: build only supported targets using guix-start, update guix-start and guix-check to work correctly outside of containers
#981
| Job | Run time |
|---|---|
| 4m 7s | |
| 14m 11s | |
| 12m 54s | |
| 12m 58s | |
| 12m 43s | |
| 12m 56s | |
| 13m 12s | |
| 12m 44s | |
| 12m 36s | |
| 4m 19s | |
| 5m 59s | |
| 11m 20s | |
| 7m 26s | |
| 15m 1s | |
| 6m 57s | |
| 6m 49s | |
| 6m 47s | |
| 2h 52m 59s |