bignum: shift setint64 in unsigned space to avoid signed overflow UB

setint64() extracted big-endian bytes with a signed left shift (n <<= 8).
When the top byte is set that overflows int64 -- undefined behaviour, which
the script fuzzer flagged under UBSan (bignum.h:158). The result was correct
on two's-complement hardware, so this is a latent UB inherited from the
original 0.1 code, not a behaviour change. Do the shift on a uint64.

0 files changed, 0 insertions, 0 deletions