fix: preserve jobserver file descriptors on rustc invocation to get TargetInfo
#7503
| Job | Run time |
|---|---|
| 4m 46s | |
| 14m 57s | |
| 3m 26s | |
| 2m 8s | |
| 19s | |
| 4m 49s | |
| 17s | |
| 23s | |
| 38m 28s | |
| 29m 4s | |
| 30m 42s | |
| 37m 50s | |
| 42m 30s | |
| 30m 11s | |
| 45m 50s | |
| 16m 33s | |
| 0s | |
| 0s | |
| 5h 2m 13s |