[BOLT][NFC] Remove redundant dependent template type

Summary:
Reduce code size by removing redundant dependent template type
from RewriteInstance methods.

Code size savings (via bloaty on llvm-bolt Debug build):
```
symbol,vmsize,filesize -> vmsize,filesize (delta vmsize,filesize)
updateELFSymbolTable         57096,59600 -> 56656,59048 (440,552)
updateELFSymbolTable::lambda 35957,55277 -> 35949,54485   (8,792)
getOutputSections            20592,21440 -> 20372,21156 (220,284)
getOutputSections::lambda      1792,5300 ->   1792,5372   (0,-72)

total delta (668,1556)
```

Reviewed By: maksfb

FBD33589393