build: use _topdir macro instead of hardcoded relative path
#3694
| Job | Run time |
|---|---|
| 6s | |
| 4m 43s | |
| 3m 12s | |
| 5m 12s | |
| 2m 30s | |
| 3m 27s | |
| 3m 25s | |
| 25s | |
| 15s | |
| 23s | |
| 59s | |
| 20s | |
| 56s | |
| 25m 53s |