std: Fix two bugs in bigint pow

* Correctly scan all the exponent bits, this caused the incorrect result
  to be computed for exponents being powers of two.
* Allocate enough limbs to make llmulacc stop whining.
dbc11be038LemonBoy committed on 10/6/2020, 2:16:26 AM· committed by Andrew Kelleyparent7f7e2d6
2 files changedLine totals unavailable