Add __powitf2 symbol for f128 integer exponentiation
#1457
| Job | Run time |
|---|---|
| 8s | |
| 16s | |
| 37s | |
| 6m 10s | |
| 1m 17s | |
| 49s | |
| 49s | |
| 4m 4s | |
| 53s | |
| 1m 21s | |
| 1m 8s | |
| 1m 1s | |
| 3m 51s | |
| 3m 44s | |
| 3m 41s | |
| 3m 46s | |
| 4m 3s | |
| 4m 14s | |
| 46s | |
| 54s | |
| 49s | |
| 1m 4s | |
| 1m 17s | |
| 1s | |
| 46m 43s |