Use integral math to avoid precision loss in resampling

Co-authored-by: Jianxiang Wang (王健翔) <qrox@sina.com>

resampler: Work at double precision on x86-64 machines.

We get audio artifacts if we don't work at the higher precision, but
this is painful on CPUs that have to use a software fallback for this,
so for now (that is, until we have a better solution), get better output
on amd64 chips, where the cost is less painful.

release-2.26.3_patched

fix MSVC build failures in CI after commit 1e5e8e2f