spirv_asm: use line_spans for slightly better source locations.
#845
| Job | Run time |
|---|---|
| 13m 38s | |
| 8m 54s | |
| 13m 55s | |
| 6m 39s | |
| 13m 36s | |
| 1m 4s | |
| 6m 43s | |
| 13m 13s | |
| 28m 44s | |
| 9m 48s | |
| 16m 54s | |
| 5m 31s | |
| 2s | |
| 2h 18m 41s |