Fix non-splat vector SREM expansion when one of the divisors is a power of two. (#82706)

The expansion previously used, derived from Hacker's Delight,
does not work correctly when the dividend is INT_MIN and the
divisor is a power of two. We now use an alternate derivation
of the A and Q constants specifically for the power-of-two divisor
case to avoid this problem. Credit to Fabian Giesen for the
new derivation.

Fixes https://github.com/llvm/llvm-project/issues/77169