zcash_client_backend: Move min_confirmations into Proposal
#2170
| Job | Run time |
|---|---|
| 25m 52s | |
| 27m 50s | |
| 21m 26s | |
| 7m 16s | |
| 7m 50s | |
| 3m 3s | |
| 6m 38s | |
| 6m 13s | |
| 21s | |
| 20m 35s | |
| 6m 11s | |
| 7m 57s | |
| 5s | |
| 20s | |
| 2h 21m 37s |